CSK Slotted Screws, short for countersunk slotted screws, are a kind of fastener that features a flat, countersunk head and has a single slot inside. The countersinking nature allows the head of the screw to be flush with or just beneath the surface for a smooth finish. This makes them ideal for applications requiring an appearance of seamless finish or where a secure hold is a concern. https://www.dalloyedbolts.com/csk-slotted-screw-manufacturers-suppliers-stockists-exporters.html