Optimum Pools 77503 21' Skimmer Panel with 78" Skim & Return for IG poolThe 21ft skimmer panel is compatiable with the following pool sizes: 21' round. This skimmer panel can replace a standard 21ft wall panel to add an additional skimmer and return to the pool. This 21ft skimmer panel can replace a 21ft above ground skimmer panel. Specific SP1084 adaptor plates (#77518 & #77519) are required to mount an SP1084 skimmer to the in-ground skimmer panel. Specific (#77168) return fitting kit required for return fitting assembly.