M3 x 30mm Socket Head Cap Screw (pack of 50), Zinc Plated.
These round groove pulleys are also referred to as U groove pulleys. They are made of 6061-T6 Aluminum with a D-Shaft hole through of 6mm, and 2 set screws for ultimate strength. Use it with the 5mm Round Belt and for gearing up or down combine them with the other round groove pulleys that range from 10mm to 60mm.
Specifications:
This GT2 (also called 2GT) timing belt has a 2mm Pitch and 6mm width