Check the listing for details. 72701 Hartford Loop Assembly. Condition: New. Listed at 67.41 USD. Hartford Loop Assembly This retro kit is a replacement Hartford loop assembly for select Hot Spring hot tubs and Endless Pool models. The thick wall of the hole is used to replace the air check valve. Cement or PVC primer should be used to secure the fitments properly in your plumbing system. Compatible with 1994 to current Hot Spring Highlife, Hot Spot, Limelight, Solana, and Tiger River spa models and Endless Pool models. Make Model Date Range Hot Spring Grandee 2001-2002 Hot Spring Vanguard 2001-2002 Hot Spring Jetsetter 2001-2002 Hot Spring Prodigy 2001-2002 Hot Spring Sovereign 2001-2002 Hot Spring Landmark 2001-2002 Endless Pools E2000-58 2017-Current Endless Pools E500-52 2016-Current Endless Pools E500-58 2016-Current Endless Pools E700-52 2016-Current Endless Pools E700-58 2016-Current Endless Pools X200-50 2016-Current Endless Pools X500-50 2016-Current