I’ve not seen any detail photos of the removable R2 heated bed – so I took photos. The Z platform base is metal with a plastic cross member frame holding the electrical contacts. The four corners of the frame have springs and thumb screws for rough leveling. The removable bed appears to be made of glass with a heater laminated underneath. The heater is thin so I assume it’s a circuit board. The bed is held to the platform's cross member frame on four corners via magnetic ball sockets. Six spring loaded gold contacts on the the platform's cross member frame make connections to four pads on back side of the bed's heater. The gold heater contacts are paired to handle the current draw: two contacts for the + side & two contacts for the minus side. The two remaining contacts are for the bed's thermistor located in the center of the heater.