Replacement battery for the Streamlight SL-20X LED. It is a high-capacity sub-C, nickel-cadmium rechargeable battery stick that is 8.5 inches long, has a circumference of 2 7/8 inches, and is red in color. Please note: Older Streamlight rechargeable batteries have 3 part numbers listed on the casing. The number listed first is not necessarily the part number of that particular battery. To select the appropriate battery refer to the owner's manual that came with your light or look up the compatible accessories for the specific model of flashlight you own.