YA15-3/8 Steel Spur Gear 50mm ID Click here for spec sheets:

Click here for spec sheets: SUCTPA Spec Sheet

But why settle for a knock-off when you can have the original - from Boston Gear

Input Style: F Standard Quill Flange

This design allows for the driving pinion to rotate internal to the gear

YA15-3/8 Steel Spur Gear 50mm ID Click here for spec sheets:Boston Gear spur gears are designed to transmit motion and power between parallel shafts. The different styles offered include spur, gear rack, pinion wire, stem pinions, and internal gears, and most come with a selection of bore diameters, keyways, and setscrews to accommodate a wide variety of application requirements. They are available in plastic, non metallic, brass, steel, and cast iron and are manufactured in a variety of styles, including