A and B lock for opening towards inside of the room and we will send it randomly.   C and D lock for opening towards outside of the room and we will send it randomly.   if you choose it wronly, you can open the lock cover and change the lock tongue direction inside.   please watch the video to familiarize with how to change the lock tongue direction.   Electric Rim lock   Function   .With electronic control, keys, or manually open   .High insurance, high security features    .low noise,low consumption,long life ,convenient installation.   .no function of inside opening for single lock, releasing with opening knob or key   Feature   .Extension length of dead bolt: 13mm   .Voltage: 12VDC   .Working current:1.5-3A   .Consumption power:10W   .Sensitivity: 1s   .Service life: 300,000 times   .Regulated and filtered voltage:500VDC(one minute)   .Locking method: by collision    .no function of inside opening for single lock, releasing with opening knob or key   .Surface Temp: +20°C   .Operating Temp: -10~+55°C(14-131F)   .Suitable Humidity: 0~90%(non-comdensing)   .Weight: 1.3kg   Please confirm the door lock installation from the following pic when buy it;   judge the lock from outside of the room   A &Blockopeningtowardsinside; A &BlockcaninstallexchangablelyC &Dlockopeningtowardsoutisdedirection; C &Dlockcaninstallexchangablely