If you want a true MK12 clone gun, you need the ARMS rings, but you also need the pricy Leopold scope, and funky profiled barrel with the obnoxious ops Inc brake. If you just was a sweet SPR with that mod 1/0 look (like I did) you can use better parts. I've heard of people having issues with the ARMS rings loosing zero. I went with PRI rings on my MOD 0ish gun, and I have some Warne maxima QD rings on another gun that are inexpensive and solid.