This is a Hayward Skim Vac II Vacuum Plate for 1-1/2 inch Straight Adapter. It is used on Hayward Inground Skimmers SP1082, SP1084-85, SP1070, and SP1075.
Skim Vacs have revolutionized the process of vacuuming pools. By utilizing the skimmer basket instead of the pump strainer basket, the need to turn the pump on and off has been eliminated. Simply attach the appropriate Skim Vac to the vacuum hose, locate over the skimmer basket and begin vacuuming.