LEGO Medium Stone Gray Power Functions Battery Box with Beam Connectors (16511 / 58119) | Brick Owl - LEGO Marketplace
Electric 9V Battery Box 4 x 11 x 7 PF with Orange Switch and Dark Bluish Gray Covers : Part 59510c01 | BrickLink
How to modify your Lego Technic Battery Box. Save on Batteries! More Power! - YouTube
LEGO part 59510c01 - Light Bluish Gray Electric 9V Battery Box 4 x 11 x 7 PF Complete Assembly with Orange Switch and Dark Bluish Gray Covers at BrickScout