This is the dual slotted Vixen style rail used on the RB002V Riser Block System. The rail is about 10 1/2" long with two slots, one that is 5" long and one that is 2 1/4" long. This allows the rail to be used with the riser blocks, placing them on one side of the rail to achieve perfect balance with the telescope you are using. Also has a 1/4-20 threaded hole that is about 3 7/8" from one edge. Maximum distance between rings is about 8 3/8" so measure the distance between the top holes on your rings to see if this will work.