Glider Support Assembly includes a Glider Support, 4 – SH142 Nylon bushing swing hanger, 4 – H165 spring clips, 2 – ½" x 3" lag bolts and the top 1 – ½" bolt for attaching to wood. All three holes on the support are 14mm. The two holes together are 7 7/8" center to center on the 11 7/8" side and 1" down from where the pole would set on the pipe. The one hole's center being at 6" on the welded part to the two perpendicular poles and 1 38" from the outer edge. The 14mm is a little bigger than 1/2" and a little smaller than a 9/16" hole. This product should last 2 years in harsh conditions and up to 5 years in optimal conditions. Some conditions may require replacement sooner.