89-L52035. Lynn McKenzie Signature Series Stainless Steel MMB Medium Shank. Level 1. Lynn's Thoughts: Need a little more leverage to bring the horse into the bit? This medium shank is a middle of the road shank, but it's far from average. It will accomplish a lot without a lot of hard work. This mouthpiece is good for horses who like to push off, root or lug on the bit. Please also note that the type of resistance described here may be due to either dental problems farther back in the mouth or tight muscles at the poll. Keeping the rein up by the neck at the swhoulder is the key to making this bit work properly.