Here are the rotors presently available at the OCI. The first five are Sorvall rotors, the rest are Ultracentrifuge rotors. Ultra rotors can be found in 8-206. To calculate the Unknown quantities, enter the known value and select it's "Compute from ..." button. If I missed a rotor, or if you just bought one, give me the details (Name, Max_speed, R_{min}, R_{max}). Flip.