Works like standard spring-loaded center punch. For window-breaking, push/release repeatedly until window breaks. No separate "reset" required. Works forever, or at least until/unless spring fails to perform as designed.

Aside: The written instructions accompanying Houdini don't specify, but I've read (but no personal experience) that faster results if tool used in a lower-corner (vs. middle of window where there might be some "give" to glass) AND where the tiny coded numbers/letters are etched at bottom lower-left because, supposedly, the etching process creates an ever-so-slight "weak spot" in the glass. YMMV.