Stainless Steel Torx Pan Head Machine Screws with Flat Washer and Split Lock Washers
Also known as torx pan head sems screws.
The flat washer distributes holding pressure and protects delicate surfaces from damage while the split lock washer adds tension to prevent loosening from small amounts of vibration. The washers rotate freely but are permanently attached. They're made from 18-8 stainless steel and have good chemical resistance. Screws may be mildly magnetic.