This collar is made of steel with black oxide finish. It grips tight and even without damaging the valve surface. It fits the 3/4" valve OD of models like 2240, 2250, 2260, 2300T, 2300S, 2300KT, 2400KT, Discovery, Maximus, Marauder Pistol and other models with 7/8" OD tubes. It fits a 3/16" hex wrench which is not included but available in the HEX WRENCHES listing.
It makes assembly and disassembly easier, especially for valves with hard o-rings or threadlocker. Some prefer to use two collars, one on each half of the valve. In some cases you can use one collar on the valve cap and thread a screw into a screw-hole on the valve body for leverage.
We don't recommend using threadlocker to assemble valves. Some CO2 valves have it, some don't but it's not necessary either way. The internal o-ring seals the two halves of the valve. Threadlocker is often used at the factory to keep the cap (chamber plug) on CO2 valves from loosening when you turn the piercing cap to remove the CO2 cartridge. There's not generally enough friction for the cartridge to turn the cap but it's used as a precaution. We never use it and have assembled thousands of valves since 2009 without a single issue.