These seats are designed for use inside the tank for low back, hip and leg treatment. Two side brackets with four levels of adjustments (three levels for the -AS3) are provided, along with an adjustable removable seat.The seats are fabricated entirely from Type 304 stainless steel. -AS1 is for 20"" wide whirlpools.-AS2 is for 24"" wide whirlpools except Lo-Boys.-AS3 is for all Lo-Boy whirlpools.