The Pentair 85002600 is a Thermoplastic Vari-Flo Control Insert Only compatible with a Admiral™ Pool and Spa Skimmers. Admiral S20 Skimmers have a PVC reinforced twin port base. S20 may be purchased with equalizer for commercial and NSF applications or for when the second port is connected to the main drain. All models include the innovative lock down lid and are available with a flap weir or the circular weir for greater skimming action.