Ruff's Precision Manufacturing Diving Board Low Mount Rail Cap 34mm Black. This rail cap accessory allows you to add both rail mounted laser rangefinders or secondary aiming devices (red dots) to your magnified optic. This is a simple cap replacement that fits ALL existing RPM products (CLR series rings and all Bravo/Delta cantilevers). The cap screws included in the original purchase are the exact screws needed to install this accessory. Note: Modern compact scopes with objectives 44mm or larger are not compatible with laser rangefinders on our cantilever mount. Specifications for Ruff's Precision Manufacturing Diving Board Low Mount Rail Cap: Manufacturer: Ruff's Precision Manufacturing Fabric/Material: 6061-T6 Aluminum Features of Ruff's Precision Manufacturing Diving Board Low Mount Rail Cap Alignment lugs minimize chances of cross threading Package Contents: Ruff's Precision Manufacturing Diving Board Low Mount Rail Cap Ruff's Precision Manufacturing 34-LRC: Diving Board Low Mount Rail Cap 34mm Black