Chicago screw-and-post fasteners are useful to fasten buckles onto belts or bits onto horse bridles. Ours are solid brass.
Choose a Chicago fastener that is equal to or slightly shorter than the thickness of the materials you need to fasten. This fastener will fasten materials that are about 3/8" thick or a bit thicker.
How to install: Punch a hole in each leather part to be joined. A 3/16" diameter hole punch works well for these post and screw fasteners.
To keep the fastener from slowly working loose, add a tiny drop of thread locker fluid (available from hardware stores; Loctite is a common brand) or nail polish inside the post or on the screw threads.
Align the holes in the parts to be fastened together. Slip the post (female) part of the fastener through the holes. Insert the screw portion into the post.
Tighten the fastener with a screwdriver until the screw seats firmly against the post or against the material being fastened. If the parts are thicker than the length of the post, the screw may not seat directly against the post. A small gap is okay, but I recommend using the longest screw-and-post fastener possible for best results.
Here's a video that shows the process of installing a screw-and-post fastener: https://www.youtube.com/watch?v=izb8EA_tzMo
Sold per set of screw and post.