This is probably a dumb question but here goes.. . I have been working on a gun build for the last 4 or so months. I am ready to purchase scope rings and am sold on the Talley Lightweight One Piece Alloy rings. What I don't understand is why some of the rings have different heights even though they are the same size. Look at the data I pulled below off of the Talley Scope rings website. The fronts are all the same but the rears change. 730700 30MM Model 700-721-722-725-40X (Low) F .400 R .510 730709 30mm Model 798 (Low) F .400 R .560 730720 30MM Model 7 (2 Piece) (Low) F .400 R .515 738700 30MM Model 700-721-722-725-40X (Low) (8-40) F .400 R .510 Are they adding MOA like a picatinny rail? If so where do I find the data? Am I missing something? If it helps I am planning on putting a set of rings on a Remington 700 sendero 7mm. The scope I have chosen has a diameter of 30mm. And I am not looking at adding any MOA to the rings or using a picatinny rail. Can anyone help me?