Otf

He retracted the OTF blade into the hilt and walked away. Azrael's phone rang. He sighed and answered the call. “What?” “What the hell do you think you are doing?” “I took care of a small problem.”

Frank never went anywhere without his OTF (out the front) gravity knife, issued to him by Uncle Sam […] He pushed the button forward to eject the blade from its olive-green hilt, and swung his arm around toward his [target].

Straight-line spring or end-line spring - with a blade that fires both in and out, which utilizes a unique mechanism that simultaneously compresses the spring and releases the blade on each up-and-down movement of the button on the knife. This is often referred to as an “out the front” or OTF.

I've found it better to just give them an OTF knife than to argue.