Overview Reviews Similar Products Product Description Jandy / Cal Spa U-Joint Knuckles. Used on Cal Spa valves, use 3/4" PVC for rod. Part # PLU21800410 location: LB3-R2B2 Product Videos Custom Field Product Reviews Find Similar Products by Category Recommended Quick view Cal Spas INSERT MINI JET ASSY (OLD STYLE) $12.95 Add to Cart Quick view Cal Spa Maxi Flo Insert (White) $9.95 Add to Cart Quick view Cal Spa Insert Double Hole Pulsator W/Ring Face 2 1/2" $14.95