These "trigger block" widgets, name escapes me, sorry, don't fit all models of Glocks, and are not one-fits-all, make sure you get the right one, if available. Look at the Siderlock trigger safety retrofit, which I've found to be satisfactory. It's not as easily installed(using the the lame instructions supplied) as claimed, but any Glock certified armorer should make short and inexpensive work of it...