Donny's folding knife is a folding knife that Donny used to cut a towel from the cinema's bathroom, to conceal his Glove pistol and pass as a waiter.
Overview
The folding knife consists of a handle and a foldable blade. There appears to be no (visible) locking mechanism.
In Inglourious Basterds
Donny uses one such knife in the Le Gamaar bathroom to cut a towel and conceal his OSS pistol.