10k 12 1/4 x 3 3/8" Left Hand Eletric Brake assembly
Measurements are 12 1/4" diamenter by 3 3/8" width.
Paired with the Right side 10k electric trailer brake assembly can support axles up to 10000 lb.
This assembly uses a 7 bolt mounting pattern that should match your trailer axle. There is a pair of lead wires attached to the brake magnet. One is ground and one is power.
It doesnt matter which one you use in either location as long as they are attached properly.
These 10k eletric brake assembly's are manual adjust so you will need to properly adjust them over time as the brakes shoes wear.
The way the brake assembly functions is there is a magnet that will apply friction to the lever in return pushes the shoes out into the drum causesing friction which allows your trailer to come to a easy stop.