The CP - 8261 - 333 is an Electronic 6 stage programmable controller, single temperature setpoint,stages can be setup for Heating , Cooling and Fan operattion.
Thing to watch for is that BARBER COLMAN produced many versions of this controller for OEM customers usually indicated by the last 3 digits of the part #. They also produced actuators for these customers and it gets to be a pain cross referencing a replacement as the internal wiring is quite a bit different.
These are overkill on what I have, I just got some paper work on them now and figuring them out. They are on a simple hydronic heat pump, just heat and cool with and outside damper. Being expensive I was thinking of just replacing them with a simple electronic thermostat but since they last a long time, I'll just keep them in. thanks for all the replies.