Product Information: Item Description Ganged Mounting Bracket Blocks Part Number #503-0173 Blocks only. Does not include the 9x12H style MPS pictured at left. The standard Extension Bracket can also be used in ganged-mounting applications to provide variable length capabilities and a more secure mount. What's Included About (4) GMB Blocks Mounting Hardware (2) Chase Nipples The GMB Open style blocks come in sets of (4) to mount (2) stations to one pole. The GMB blocks come with mounting hardware and a chase nipple to provide a protective conduit for field wiring.