One kit does one axle. So you need to order 1 Monroe RB-Kit per axle and one shock absorber per wheel.

The kit includes the lower mounting plates (which go at the bottom of the leaf spring mount, held on with the u-bolts that go over the axle).

It also includes the bolts and hardware to mount the shock to the lower plate, and up at the top where it bolts to the frame (normally a hold has to be drilled in the frame to attach that upper mount bolt).

In cases where the kit is being installed on a C-Channel or I-Beam Channel frame, an RB513 bracket is needed.

The mounting bolts are 5/8 and accept the Monroe Trailer Shocks with those ends.

For the most part these are universal, and can be used on any kind of trailer where tire hop and vibration is a problem.