http://www.odinworks.com/Forend_12_5_p/f-12.htm
All forends include a 2.75" accessory rail (with 2 8-32 screws), forend adapter, barrel nut, Vibra-Tite, and 8 6-32 screws.
Features
Free float
Weight: 12.20 oz (includes weight of parts kit).
Made from 6005-T651 Aluminum.
Inside diameter: 1.6"
Outside diameter: W-1.9" H-2.16"
Engineered with advanced ergonomics for comfort and improved performance.
Continuous/uninterrupted Picatinny Rail across the top.
Accessory rails can be placed at 3, 6, and 9 o'clock positions and can be joined to create continuous Pic Spec Rail.
For bi-pod or sling, additional 10-32 tapped holes for standard sling swivel.
4-QD sling mount positions.
Engineered to allow for low profile gas block to fit inside.