this look interesting but i guess with or without also doesnt matter much:
Chamber Lock:
Designed by Brian Holt. With this new hop up design you will not have to worry about losing and dropping several bb’s with a magazine change. This new design provides you with a way to keep bb’s in your AEG and ready to use and not on the floor and even better it stabilizes the top of the magazine to ensure a secure and flawless feed of bb’s into the AEG.
CAUTION: This hop up unit is designed for the experienced and responsible Airsoft player. With the magazine removed the AEG is still able to fire several bb’s. Always wear safety goggles and treat all Airsoft weapons as if they were loaded.