Hello, Oldgoaly. At first I thought of using those for drilling glass, or ceramic tile. I did a little digging, and came up with the following;
Watts Brothers Tool Works is a tool manufacturer located in Wilmerding, Pennsylvania. They are known for manufacturing drill bits that can drill square holes,[1][2] including blind holes which cannot be made with other methods such as broaching. The Harry Watts square drill bit is based on a Reuleaux triangle shape, and is used together with a guide and a special chuck to make a square hole.[3][4] Similarly, the company also manufactures drill bits for other angular holes such as pentagons and hexagons. Regards, Lou Just a guess!!!!!!!!!!