Heavy Duty spinnaker pole slider for 1 ¼” t-track Made of investment cast stainless steel Ring just under .500" in diameter. Spring pin that locks in or out Shackles for uphaul and downhaul. Removeable if not required. Merriman brand. NOS. Never seen battle. Piece of boat jewelry! Closest comparison is Shaefer without the uphaul and downhaul at $250 plus plus. https://hardware.schaefermarine.com/products/spinnaker-pole-slider-investment-cast-for-1-1-4-t-track-73