Hex screws refer to a type of fastener that has a hexagonal shape at the top, allowing it to be turned with a tool called an Allen wrench. Full definition
The scope ring comes with friendly hex screws to allow you to easily attach it and remove it from your gun. (geekwrapped.com)
Removing the two T2 hex screws at the bottom, using the pick to insert the back cover and the fuselage, and then slowly open the back cover. (myfixguide.com)
We wish Braven created a tool-less mounting solution but the decision to use hex screws does offer a solid mounting solution that should stand up to the abuses of the outdoors. (techradar.com)