This part fits on 7" Steel, 8" Steel, 8" Resin, 9" Steel (2010 and newer) or Mirage frames. This is a newer style of joint which utilizes a 5/8 inch rail (or track). It measures 5" 7/8" wide by 4" deep. This is a lower joint, meaning it only can be used along the bottom of the pool near the ground.
THIS PART ONLY WORKS WITH 5/8" RAILS. If you buy this part, do NOT purchase 1" rails. If you are not certain, measure the rails on your pool. If they are 7/8", they are considered 1" rails. Be aware, that newer pools (2010 & newer) use resin joints, but these new resin joints only fit with 5/8" rails instead of 1" rails. If your pool has steel joints and you would like to replace them with resin joints, you may, but you will need to also purchase all new 5/8" rails for your pool.