Clamp-on mounting plate accessory makes a boat “outrigger ready” in an instant! Pre-drilled for the Grand Slam & Sport Slam, or undrilled for mounting lights, radars, antennas. Clamps to most Ttops & radar arches without welding. Fits schedule 40 (3/4”, 1”) or oval pipe (1 x 1-1/2”). Recessed screw design allows the clamp to capture both the T-top pipe and the special mounting plate.