The solid investment-cast 316L stainless UM6080 was designed primarily as an adapter for mounting downriggers. When your downrigger is not in use, you can use that mount location for another boating accessory like a rod holder or a flag. The UM6080 is equally useful as a BBQ, bait board, or other custom base. The 4-hole pattern is a 2.5" square pattern (center-to-center) with ¼-20 threaded holes. Cannon® downrigger mounts Part #1903003, #1903004, #2207002 and #2207323 will bolt directly onto the UM6080. Cannon's Swivel Base and other downriggers will need the addition of the appropriate Burnewiin adapter plate. Please review our adapter plates to choose which one you may need. Let your imagination go and create other uses for this versatile base. The UM6080 is NOT compatible with the GM400 Mount.