Primarily designed for use with Maple Leaf's own AEG barrels, these can however be used with other barrels like ZCI, you may need to trim parts of the rubber to get the patch to correctly fit since it's quite a large fit.  Inside of the bucking there's a circular rubber inner ring, just push the bucking on with a little bit of force.  

This comes with one of our own 60 shore Omega nubs.