Upgraded Kit For SRB Series

With the accessories FXT WORKS provided, enjoy reliable performance at 250-270 fps & 10-13 shots/sec for the SRB400 / SRB400-SUB / SRB1200 / SRB375M. This bundle will include these： Unequal Spring * 1 7.4V 2000mAh High-rate Discharge Li-ion Battery *1 Gel Balls * 10,000 How to upgrade Use a screwdriver to disassemble the gun body casing, rotate the button at the back of the gearbox, remove the original spring, and replace it with a new one. Upgrading the firing rate is effortless!