These hex head type 17 screws with seal are designed for self drilling into timber. They come in class 3 & 4 galvanised steel or grade 316 stainless steel and have a watertight neo washer. Features: Neoprene washer provides a watertight seal which is ideal for roofers applications Designed for drilling into timber – no need to drill a pilot hole Made from class 3 & 4 galvanised steel for outdoor use, or grade 316 stainless steel Hex head type 17 screws with seal – quick reference Code Size Specs Qty T17HEXC3N310020 10g-12tpi x 20mm gal – C3 1000 T17HEXC3N312030 12g-11tpi x 30mm gal – C3 1000 T17HEXC3N312035 12g-11tpi x 35mm gal – C3 1000 T17HEXC3N312050 12g-11tpi x 50mm gal – C3 1000 T17HEXC3N314065 14g-10tpi x 65mm gal – C3 500 T17HEXC3N412025 12g-11tpi x 25mm gal – C4 1000 T17HEXC3N412030 12g-11tpi x 30mm gal – C4 1000 T17HEXC3N412035 12g-11tpi x 35mm gal – C4 1000 T17HEXC3N412040 12g-11tpi x 40mm gal – C4 1000 T17HEXC3N412050 12g-11tpi x 50mm gal – C4 1000 T17HEXC3N412065 12g-11tpi x 65mm gal – C4 1000 T17HEXC3N414025 14g-10tpi x 25mm gal – C4 1000 T17HEXC3N414040 14g-10tpi x 40mm gal – C4 1000 T17HEXC3N414050 14g-10tpi x 50mm gal – C4 1000 T17HEXC3N414065 14g-10tpi x 65mm gal – C4 500 T17HEXC3N414075 14g-10tpi x 75mm gal – C4 500 T17HEXC3N414090 14g-10tpi x 90mm gal – C4 250 T17HEXC3N414100 14g-10tpi x 100mm gal – C4 250 T17HEXC3N414115 14g-10tpi x 115mm gal – C4 250 T17HEXC3N414125 14g-10tpi x 125mm gal – C4 250 T17HEXC3N414150 14g-10tpi x 150mm gal – C4 250 T17HEXC3N414175 14g-10tpi x 175mm gal – C4 250 T17HEXC3N414250 14g-10tpi x 250mm gal – C4 200 T17HEXC3N612025 12g-11tpi x 25mm SS 316 1000 T17HEXC3N612050 12g-11tpi x 50mm SS 316 200 T17HEXC3N614025 14g-10tpi x 25mm SS 316 1000 T17HEXC3N614050 14g-10tpi x 50mm SS 316 500 T17HEXC3N614075 14g-10tpi x 75mm SS 316 500 These screws are often called Type 17s or T17s.