This listing is for one (1) Ryobi ONE+ 18v dual battery power cap. Designed to be securely surface mounted with the batteries facing upward for easy access. This unit can be used to power anything that requires DC power, using Ryobi 18v batteries. Power can be run from each battery individually, or it can be wired in series or parallel (buyer is responsible for final wiring per their project needs. An inline fuse or 2 fuses is recommended depending on how the project is wired). UNIT COMES ASSEMB