Jasonoostra, I would highly recommend krytac, extremely durable and well made, robust gearbox with alot of great parts (including an internal mosfet which reduces trigger arching therefore extending the life of your gun). For Batteries, I would recommend 11.1 lipos, 1000 mah for the krytac. Fits very easily in the stock and are really easy to get to when one dies. Look at Airsoft Gi or Evike for the krytac and Hobbyking.com for the batteries. (If you do buy from here, make sure to select western or eastern warehouse depending on your location.) now if you do decide to purchase the krytac, which i hope you do, Elite Force Mids run absolutely flawless. I hope this helps.