This is a 500-gram slotted weight for aluminum weight hanger WH50A or any weight hanger with stem diameter of 5 mm or less.
The slot width is 5.2 mm and the center hole diameter is also 5.2 mm. In other words the center hole is just an extension of the slot.
Made of brass.
Diameter: 32 mm
Standard masses are 500, 100, 50, 20, 10, 5, 2, and 1 gram.
Click on the images for prices, availability and ordering online.