The L311 Compact Long Lens Case 300 from Kinesis provides a secure transport and storage solution for a 300mm f/2.8 or 400mm f/4 DO lens with an attached Arca-Swiss plate, teleconverter, and a DSLR of any size, along with the lens's hood in the stowed position and with its leatherette cap in place. It is also designed to provide room for a 500 f/4 or 200-400 f/4 lens without an attached camera body, and with the hood in the stowed position. A 200 f/2 lens with a body attached can be placed in this case with the hood in the shooting position.

This Kinesis pouch is compatible with both the Kinesis TwinBuckle Attachment System and the Kinesis Attachment Tab System (KATS) for ease of use with Kinesis pouches, harnesses, or straps. The weather-resistant lid features a buckle closure for quickly removing and stowing a lens while shooting. In instances between shots where quickly withdrawing a lens is less of a priority than making sure that it sits securely within the pouch, the lid can also be zippered shut.

The exterior consists of 500 denier nylon for water-resistance. A Kinesis Y515 Heavy-Duty Padded Shoulder Strap is included to allow the case to be carried over one shoulder. Also included is a Kinesis A257 Body Pouch which can accommodate one pro-sized DSLR and can be attached to the lens case.