I use the butler creek #18 I think for the eyepiece. On the front, I put a leupold alumicover. The threads are the same, the bell is 1 mm larger on NF. Take a piece of thread tape and wrap it around 1-2x. It will fit perfect, although I did remove the leupold emblem(didn't want to jinx my scope
). I have 2 set up like this and work great.