ZIPPER REPAIR PARTS
What can be replaced on your zipper:
Top Stops: Used to keep the zipper pull or head from popping off the end of the zipper.
Bottom Stops: Goes over the completes zipper teeth to stop the pull at the bottom of the zipper.
Replacing the Pull: Some times the actual pull falls off the zipper head. If you have the bridge, then you can replace the pull.
Replacing the whole head/pull mechanism: Watch the video below to see how easy it is to replace just the head. Need to figure out what zipper head? Look below at the shape of the heads.
Box & Pin: These are the parts that make your jacket zipper separate at the bottom. NO these can NOT be successfully replaced on your current zipper. (Yes you can buy these on amazon & no, they don't work.) The whole zipper needs to be replaced.
Sizing: Getting the right pull/head combo to fit your zipper is all about the size & type of zipper teeth. When you see the #3 or #5 or #10, that is the SIZE or GAUGE of the zipper in millimeters. So think 3mm or 5mm or the larger the number the bigger the tooth.
#3 coil or 3mm = .165 inch or 5/32"
#5 coil or 5mm = .275 inch or 17/64"
#5 tooth or 5mm = .225 inch or 7/32"
#7 coil or 6.8mm (rounded up to 7mm) = .25 inch or 1/4"
#8 coil or 8mm = .284 inch or 9/32"
#8 tooth or 8mm = .3125 inch or 5/16"
#10 coil or 10mm = .42 inch or 27/64"
#10 tooth or 10mm = .335 inch or 11/32"
Coil: Usually nylon sewn onto the edge of the zipper. Rainbow coil is nylon & electroplated to make it look like it is metal but sews easily.

Plastic or Resin Teeth: Plastic for jackets or Resin for outdoor or uv protected zippers. These look like a series of the ends of keys applied to the side of the tape.

Metal Tooth: Can be pretty much any color painted metal or aluminum (stay away from it. Light weight.), pot metal, brass

You have the Zipper Head but don't know how the type of zipper? Look at the BACK of the Head: