Fotodiox Battery Adapter for Hasselblad – Fotodiox, Inc. USA
Amazon.com : 9V Battery Adapter for Hasselblad 500EL 500EL/M 500EL/X 500ELM 500ELX 500 ELM EL ELX EL/M EL/X Camera : Camera Lens Adapters : Electronics
Rechargeable NH5 6V NiMH Battery for Hasselblad 500 EL 500 ELX NH5/750 3/520H | eBay