The STJR is simply a means of holding the often difficult button on the side while loading your magazine during matches. The last thing you need is the nuicence of hurt or bleading fingers during a competition not to mention broken finger nails. The Super Thumb Junior holds the button down comfortably while you are enjoying your sport either at a match or at practice. This model fits, Browning, Colt, High Standard, Ruger, and S&W 22A target pistols.