The Apex 4:1 Smart Jumper Block can ONLY be used with the Apex Battery Rack 1 - it is used to connect an existing PRO Lower Junction Box (PRO 2/CinemaHD/Cinelive) to the Battery Rack 1. It is NOT compatible with older PRO Battery Racks as the pin spacing is different.
A 4:1 Smart Jumper Block is included with every Battery Rack 1 purchase, but this replacement Block is available to purchase as a backup if wanted.
