1 3/4 inch belt buckles are a popular width for casual belts. The solid brass center bar buckles tend to be used width casual belts as well as the silver chrome plated belt buckles. The roller buckles are used for harness buckles, large size breed dog collar buckles and industrial belt buckles.
The 1 3/4 inch size is the inside measurement of the buckle. The inside measurement lets you know how much room is available for a belt width.