The 4th most useful tool on set is probably the carabiner. While not as glamorous as its bourgeois cousins, Gaff Tape and the Sharpie, this utilitarian device will keep tape rolls together or keys on chains. Do what you wish, but do NOT underestimate this little guy. 

• Easy spring clasp
• Easily hidden (it’s camouflage)
• Lightweight and strong
• 2 1/2” long