These weights mount on the inside channel of the MDT ACC Premier GEN1 and Elite Chassis forend. With the maximum forend capacity of 5 weights, and a max of 4 on the ACC Premier GEN2, they add 2.6lb to your ACC Chassis System. The interior forend weights can be added and removed without removing your barreled action, simply remove the forend cap, slide them into the desired location under the barrel, and screw them in place from the bottom.