These are router installation templates for the oval type of Futures Fins leash plugs. Included is the bottom of the plug/slot template and then the top flange template. To use, position the template, tape to the surfboard, router out the slot first then router out the flange. The router bushing kit listed below is used to ride up against the template.
Included are depth setting gauges for the router bit.
Tools required to use these templates are a router bushing kit. It's sized for the 1/4" Milescraft router bushing (I.D. 1/4" (6.4mm) O.D. 5/16 (7.9mm)) and you will need a 1/4" straight cut router bit. https://www.milescraft.com/product/metalbushingset/