Scupper valves allow water to drain out of the scupper holes of a sit-on-top kayak while simultaneously preventing water from splashing up through the holes. A scupper is an open-air structure that allows water to drain rather than collect behind a vessel's bulwarks, gunwales, or within a building's curbing or walls. Scuppers are divided into two types: Scuppers are situated at deck level on ships to allow for ocean or rainfall drain-off. Scuppers may be installed on buildings with railed rooftops to allow rainfall to drain rather than accumulate within the railing. Scuppers can also be usable on a parapet in the same way.[2] Key Features: Allow water to drain from the scupper holes while keeping water from splashing up through the holes. Injection Molded Nylon Specifications: SKU:3-520500-1 UPC:035514520058 Weight:0.07 LBS A:2 13/16" B:1 7/8" Fastener:#6 FH Package Dimensions: 8.128cm L x 8.128cm W x 1.777cm H Brand: Sea-Dog Line Product Type: Fishing Equipment Injection Molded Nylon.