The A5 vertical adapter lets you mount an expansion adapter, reg, or CO2 tank at the stock front grip location. The A5VA still allows for the no tool field strip feature. To do this you unscrew the swivel adapter and rotate the swivel out of the way to allow unlatching the high pressure tombstone adapter. We added heat sink fins to the swivel connector to help transfer heat to the gas; this also gives it a great look. The VA gives the user a very good balance and feel.