/index.asp?PageAction=VIEWPROD&ProdID=2970 4 cells AA rechargeable/non rechargeable battery holder with cover , USB interface connector, "out" "In" "Off" switch with belt clip. Off --- No output power Out ---5V DC output In --- Charge battery Side by side series connection, with a DC voltage regulator and give a constant DC 5V. Holder Material High Impact ABS Plastic Contact Material Springs are nickle plated overall Color Black Dimension 3.15"x 2.5"x 0.76"(1" with belt clip) /index.asp?PageAction=VIEWPROD&ProdID=2970