Which zipper is correct for jeans?

Q: Which zipper is correct for jeans?

Jeans take a size 4.5 brass metal zipper with Y-shaped teeth, closed-end, and a locking slider. The metal chain is the point: a denim fly is under tension every time the wearer sits, and the brass teeth and the locking slider are what stop the fly from creeping open. The tape should be pre-shrunk and dyed to survive stone wash without bleeding onto the indigo, and the zip length has to match the rise so the pin does not pull out at the bottom box.

• Size 4.5 brass metal, closed-end, Y-teeth.
• Locking slider, and a bottom stop rated for a loaded waistband.
• Pre-shrunk, wash-fast tape.

The classic mistake is a nylon coil in a denim fly, which fails at the bottom box after a few months and looks wrong against heavy twill. The second pitfall is plating that bleeds: a cheap finish stains the fabric around the fly after the first wash. Specify a properly plated or solid brass chain and test it through the actual laundry process.