Opteka is proud to be allowed to use the same factory and mold as Canon uses for their BG-E2N. Opteka is one of the world's leading producer of high-performance batteries and accessories. Opteka believes there is no limit to the potential of portable power - and as a company they will always strive to find innovative and efficient ways to power your life in the future! The Opteka 50D/ 40D/ 30D / 20D grip holds 6 AA Batteries or 2 BP-511 batteries. This provides a extremely extended shooting time. The vertical shutter release also makes shooting with the camera in a vertical position just as comfortable as shooting horizontally. Now features a built in IR receiver which is compatible with the included IR remote. Compatible with the Canon EOS 20D, 30D, 40D, & 50D Digital SLR's. This kit includes 2 Opteka 2000 mAh BP-511 Batteries for Maximum Power (Also accepts AA). The high-capacity Opteka OP-512 rechargeable lithium-ion 2000mAh battery is a replacement for Canon BP-511 (BP511), BP-511A (BP511A), BP-512 (BP512) BP-514 (BP514) Battery. It features lithium technology, which ensures maximum battery life and maximum power. It also features no memory effect that lets you recharge partially drained batteries without reducing performance. Beware of low quality knockoffs they can often damage your camera. Opteka Batteries are guaranteed. Works for the following: Canon EOS 5D, 10D, 20D, 30D, D30, D60, Digital Rebel, Pro90 IS, Pro 1, G1, G2, G3, G5, G6 Digital Cameras. Optura Pi, ZR10, ZR20, ZR25, ZR30, ZR40, ZR45, ZR50 Camcorders.