Uxcell 16mm Barb x 20mm Spigot Straight PVC Pipe Fitting Adapter White 4 Count - Walmart.com
Adapter: 20mm female by 55/64"-27 male – AquaPurr
Amazon.com: JENSWILL 20mm/0.78" Length Extension Pipe Arm Stainless Steel G 1/2 Male to G 1/2 Female Thread Adapter Cast Pipe Fitting Coupler for Shower Head Arm : Industrial & Scientific