Valve O-Ring for Sand Filter. For, Hayward, Laser II Sand L160- L250 (Clamp Style), Max Flo II SP2700, Northstar SP4000X (Max Rated), Pro-Series Plus S311SX- S311SXV- S360SX, Pro-Series Sand S164T- S166T, Pro-Series Sand S180T- S210T- S220T- S244T, Pro-Series Sand S310T2- S360T2