diff --git a/external_chi2/optimal_observables/interface_oos.py b/external_chi2/optimal_observables/interface_oos.py
index 1ef4293..1c9f022 100644
--- a/external_chi2/optimal_observables/interface_oos.py
+++ b/external_chi2/optimal_observables/interface_oos.py
@@ -4,14 +4,13 @@
 
 current_file_path = pathlib.Path(__file__).resolve().parent
 
-# future colliders to include
-collider = "FCCee"
 
 
-class OptimalWW161:
+class OptimalWWFCC161:
     def __init__(self, coefficients, rgemat=None):
         oo_wc_basis = ["OpD", "OpWB", "OWWW", "Opl1", "Ope", "O3pl1"]
 
+        collider = "FCCee"
         self.project = np.zeros((len(oo_wc_basis), coefficients.size))
         for i, op in enumerate(oo_wc_basis):
             if op in coefficients.name:
@@ -47,7 +46,7 @@ def compute_chi2(self, coefficient_values):
         return chi2_value
 
 
-class OptimalWW240:
+class OptimalWWFCC240:
     def __init__(self, coefficients, rgemat=None):
         oo_wc_basis = ["OpD", "OpWB", "OWWW", "Opl1", "Ope", "O3pl1"]
 
@@ -56,6 +55,7 @@ def __init__(self, coefficients, rgemat=None):
             if op in coefficients.name:
                 self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
 
+        collider = "FCCee"
         self.datasets = {
             "{collider}_ww_lepto_240": "invcov_{collider}_ww_leptonic_240.dat",
             "{collider}_ww_semilep_240": "invcov_{collider}_ww_semilep_240.dat",
@@ -86,7 +86,7 @@ def compute_chi2(self, coefficient_values):
         return chi2_value
 
 
-class OptimalWW365:
+class OptimalWWFCC365:
     def __init__(self, coefficients, rgemat=None):
         oo_wc_basis = ["OpD", "OpWB", "OWWW", "Opl1", "Ope", "O3pl1"]
 
@@ -95,6 +95,7 @@ def __init__(self, coefficients, rgemat=None):
             if op in coefficients.name:
                 self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
 
+        collider = "FCCee"
         self.datasets = {
             "{collider}_ww_lepto_365": "invcov_{collider}_ww_leptonic_365.dat",
             "{collider}_ww_semilep_365": "invcov_{collider}_ww_semilep_365.dat",
@@ -124,6 +125,124 @@ def compute_chi2(self, coefficient_values):
 
         return chi2_value
 
+class OptimalWWCEPC161:
+    def __init__(self, coefficients, rgemat=None):
+        oo_wc_basis = ["OpD", "OpWB", "OWWW", "Opl1", "Ope", "O3pl1"]
+
+        collider = "CEPC"
+        self.project = np.zeros((len(oo_wc_basis), coefficients.size))
+        for i, op in enumerate(oo_wc_basis):
+            if op in coefficients.name:
+                self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
+
+        self.datasets = {
+            "{collider}_ww_lepto_161": "invcov_{collider}_ww_leptonic_161.dat",
+            "{collider}_ww_semilep_161": "invcov_{collider}_ww_semilep_161.dat",
+        }
+
+        incovs_reordered = []
+        for path in self.datasets.values():
+            invcov = np.loadtxt(current_file_path / path.format(collider=collider))
+            temp = jnp.einsum("ij, jk, kl", self.project.T, invcov, self.project)
+            incovs_reordered.append(temp)
+        self.incov_tot = jnp.sum(jnp.array(incovs_reordered), axis=0)
+
+        self.rgemat = rgemat
+
+        if self.rgemat is not None:
+            # multiply the RGE matrix as well
+            self.incov_tot = jnp.einsum(
+                "ij, jk, kl", self.rgemat.T, self.incov_tot, self.rgemat
+            )
+
+        self.n_dat = len(oo_wc_basis)
+
+    def compute_chi2(self, coefficient_values):
+        chi2_value = jnp.einsum(
+            "i, ij, j", coefficient_values, self.incov_tot, coefficient_values
+        )
+
+        return chi2_value
+
+
+class OptimalWWCEPC240:
+    def __init__(self, coefficients, rgemat=None):
+        oo_wc_basis = ["OpD", "OpWB", "OWWW", "Opl1", "Ope", "O3pl1"]
+
+        self.project = np.zeros((len(oo_wc_basis), coefficients.size))
+        for i, op in enumerate(oo_wc_basis):
+            if op in coefficients.name:
+                self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
+
+        collider = "CEPC"
+        self.datasets = {
+            "{collider}_ww_lepto_240": "invcov_{collider}_ww_leptonic_240.dat",
+            "{collider}_ww_semilep_240": "invcov_{collider}_ww_semilep_240.dat",
+        }
+
+        incovs_reordered = []
+        for path in self.datasets.values():
+            invcov = np.loadtxt(current_file_path / path.format(collider=collider))
+            temp = jnp.einsum("ij, jk, kl", self.project.T, invcov, self.project)
+            incovs_reordered.append(temp)
+        self.incov_tot = jnp.sum(jnp.array(incovs_reordered), axis=0)
+
+        self.rgemat = rgemat
+
+        if self.rgemat is not None:
+            # multiply the RGE matrix as well
+            self.incov_tot = jnp.einsum(
+                "ij, jk, kl", self.rgemat.T, self.incov_tot, self.rgemat
+            )
+
+        self.n_dat = len(oo_wc_basis)
+
+    def compute_chi2(self, coefficient_values):
+        chi2_value = jnp.einsum(
+            "i, ij, j", coefficient_values, self.incov_tot, coefficient_values
+        )
+
+        return chi2_value
+
+
+class OptimalWWCEPC365:
+    def __init__(self, coefficients, rgemat=None):
+        oo_wc_basis = ["OpD", "OpWB", "OWWW", "Opl1", "Ope", "O3pl1"]
+
+        self.project = np.zeros((len(oo_wc_basis), coefficients.size))
+        for i, op in enumerate(oo_wc_basis):
+            if op in coefficients.name:
+                self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
+
+        collider = "CEPC"
+        self.datasets = {
+            "{collider}_ww_lepto_365": "invcov_{collider}_ww_leptonic_365.dat",
+            "{collider}_ww_semilep_365": "invcov_{collider}_ww_semilep_365.dat",
+        }
+
+        incovs_reordered = []
+        for path in self.datasets.values():
+            invcov = np.loadtxt(current_file_path / path.format(collider=collider))
+            temp = jnp.einsum("ij, jk, kl", self.project.T, invcov, self.project)
+            incovs_reordered.append(temp)
+        self.incov_tot = jnp.sum(jnp.array(incovs_reordered), axis=0)
+
+        self.rgemat = rgemat
+
+        if self.rgemat is not None:
+            # multiply the RGE matrix as well
+            self.incov_tot = jnp.einsum(
+                "ij, jk, kl", self.rgemat.T, self.incov_tot, self.rgemat
+            )
+
+        self.n_dat = len(oo_wc_basis)
+
+    def compute_chi2(self, coefficient_values):
+        chi2_value = jnp.einsum(
+            "i, ij, j", coefficient_values, self.incov_tot, coefficient_values
+        )
+
+        return chi2_value
 
 class OptimalWWILC250:
     def __init__(self, coefficients, rgemat=None):
@@ -383,7 +502,7 @@ def compute_chi2(self, coefficient_values):
         return chi2_value
 
 
-class Optimaltt:
+class OptimalttFCC:
     def __init__(self, coefficients, rgemat=None):
         oo_tt_wc_basis = ["OpQM", "Opt", "OtW", "OtZ"]
 
@@ -392,6 +511,7 @@ def __init__(self, coefficients, rgemat=None):
             if op in coefficients.name:
                 self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
 
+        collider="FCCee"
         self.datasets = {"{collider}_tt_365": "invcov_{collider}_tt_365GeV.dat"}
 
         incovs_reordered = []
@@ -417,3 +537,40 @@ def compute_chi2(self, coefficient_values):
         )
 
         return chi2_value
+
+
+class OptimalttCEPC:
+    def __init__(self, coefficients, rgemat=None):
+        oo_tt_wc_basis = ["OpQM", "Opt", "OtW", "OtZ"]
+
+        self.project = np.zeros((len(oo_tt_wc_basis), coefficients.size))
+        for i, op in enumerate(oo_tt_wc_basis):
+            if op in coefficients.name:
+                self.project[i, np.argwhere(coefficients.name == op)[0, 0]] = 1
+
+        collider="CEPC"
+        self.datasets = {"{collider}_tt_365": "invcov_{collider}_tt_365GeV.dat"}
+
+        incovs_reordered = []
+        for path in self.datasets.values():
+            invcov = np.loadtxt(current_file_path / path.format(collider=collider))
+            temp = jnp.einsum("ij, jk, kl", self.project.T, invcov, self.project)
+            incovs_reordered.append(temp)
+        self.incov_tot = jnp.sum(jnp.array(incovs_reordered), axis=0)
+
+        self.rgemat = rgemat
+
+        if self.rgemat is not None:
+            # multiply the RGE matrix as well
+            self.incov_tot = jnp.einsum(
+                "ij, jk, kl", self.rgemat.T, self.incov_tot, self.rgemat
+            )
+
+        self.n_dat = len(oo_tt_wc_basis)
+
+    def compute_chi2(self, coefficient_values):
+        chi2_value = jnp.einsum(
+            "i, ij, j", coefficient_values, self.incov_tot, coefficient_values
+        )
+
+        return chi2_value
\ No newline at end of file