Attwood ThruHull Connector 11/8" #23665493Cast 316 Stainless Steel. A channel under the flange holds a bead of sealant. All models have wrench flats or an end notch. Designed for installation above the water line only. Flange OD: 21/4". Barb Length: 11/4" Max hull thickness: 13/4" Stem: 327/32"