For those who still have the KWA Kriss Vector GBB, they can have it HPA powered using the Black Variable HPA Adapter which is now on its third version and reviewed by L'antre Du Dingo. This is a magazine conversion for the KWA Kriss Vector GBB that takes M4 AEG magazines and version 3 comes wih improvements to their Modular Adapter System such as mentioned by the company:

• Higher average FPS compared to previous versions
• Increased gas/HPA efficiency compared to previous versions
• Each adapter is engraved with a unique serial number
• Can be converted to use Green Gas.
• 1/4" macro line and fittings are included with purchase to connect to your 1/8 NPT QD.