This is a jig for sharpening 118 degree (most common) drill bits using a bench grinder. Alternatively, you can use an angle grinder in a vise. You can find videos online to get the technique right. It will take some practice, but I find that this jig helps me be more accurate.
It is meant to be used by with the grooves facing up. By holding the bit in one of the grooves and the long dimension of the jig perpendicular to the grind. you should be able to get a consistent angle of grind off the tip of the drill bit.
All SAE sizes up to 1/4" SAE drill bits will fit in the jig. The build this could easily be scaled uniformly to fit large drill bits. With the small gauge on the left will provide a standard 61 degree bite. If you reverse the jig you will get a more aggressive 59 degree bite.