https://fieldandcaveoutfitters.com/...ts/pair-of-3-to-4-adapter-rails-free-shipping Product page^^^ Bolt-on rails that convert your 3” stock to a 4” stock. Helps with tracking and torque control. I bought a popular new 4” stock and wanted my other rifles to be able to share the front bag/ rest top, so I made these. $50/ pair delivered within the US. Order online at link above Thanks!