Evike.com reviews the EMG Helios CYMA Platinum QBS Daniel Defense DDM4A1 & DDMK18 AEGs that they already have in stock... "New to the CYMA lineup is the Quick Buffer System (QBS) which allows for rapid spring changes that can be done by hand. This efficient new system only requires the removal of your buffer tube castle nut to gain access to the captured guide rod and spring.