These will work with factory magazines and will also convert any Ruger MKIII magazine into a Ruger MK IV 22/45 magazine. Mgazine Base Pad for MK IV, 5-pack. Volquartsen new Magazine Base Pads for the MK IV 22/45 make magazine insertion and removal quicker and easier-for lightning fast reloads.CNC-machined from billet aluminum, these base pads will make those days at the range even more enjoyable as you switch magazines with ease. This item is in the category "Sporting Goods\Hunting\Gun Parts\Pistol Parts". The seller is "petespillars" and is located in this country: US. This item can be shipped to United States.