We do not recommend using Racing Optic Perimeter Seal Laminated tear offs on Coated Shield (including ALL Z-20 and Z-24 Prism Shields). They can have a reaction which can potentially damage the shield or shorten the longevity of the shield. The standard non perimeter seal have no issue

Z-20 Shield Replacement:

NOTE: DO NOT USE power tools or overtighten screws when changing shields.
Step 1 - Lay a towel on a flat surface and set the helmet on it.
Step 2 - Remove the shield pivot tensioners on each side. (This is the smaller screw on the sides of the shield.)
Step 3 - Remove the shield pivot screws on each side. (This is the larger screw on the sides of the shield. For best results, we suggest using a quarter to loosen/tighten these screws.)
Step 4 - Remove the shield. We suggest using a soft cloth towel to wipe down the rubber seal as well as where the shield mounts to the helmet for best results.
Step 5 - Place the new shield on the helmet. There are two white washers that go between the shield and helmet, make sure these are in place before re-installing the shield pivot screws.
Step 6 - Hand thread the shield pivot screws to hold the shield in place. Once hand threaded, use a quarter to tighten until snug with the helmet shell. Do not overtighten.
Step 7 - Hand thread the shield pivot tensioners, then tighten to desired tension for shield movement.