With NiMH Pack NP-E2, Power Drive Booster PB-E2 can attain a top continuous shooting speed of about 10 fps on the EOS-1v or 7 fps on the EOS-3. The vertical grip has its own shutter button, Main Dial, AE lock button, FE lock button, and focusing point selector. It makes vertical shooting as easy as horizontal shooting. The external cover is made of magnesium alloy for improved ruggedness. This power drive booster is compatible (with limited functions) with the EOS-1 and EOS-1N (with standard battery holder BM-E2 only, Ni-MH Pack NP-E2 can't be used).