This is a ProMag® .223 Remington Magazine Loader.
Save your fingers from fatigue and maximize your trigger time at the range with these easy-to-use polymer AR-15 magazine loaders from ProMag! Originally designed for use with the extended 100-round “Beta” magazine, ProMag’s plunger-style loader can be used to insert 5 rounds at a time into any USGI-compatible AR-15 magazine. Manufactured from lightweight, impact-resistant polymer for maximum durability.