4-PACK
A Spa Jet diffuser is the clip on white stem found on the rear of a spa jet internal.
This item 218-5140 is only used on Waterway Cluster Storm jets. It will not fit on other jet brands.
The clips on the current version are beefed up and require some force to get them onto the jet and clipping the jet into the wall fitting.

Jet Part TypeDiffuser
ManufacturerWaterway
ModelCluster Storm
ColorWhite
Special FeatureSnap-In