This is what 2A Armament says:
A simple weight saving component for our AR15 BL rails . The aluminum BL rail barrel nut is made from 7075-T6 Aluminum, and then anodized black. This nut will save an additional .65oz over the standard titanium barrel nut.
SKU (2A-ALBN-1)
Weight 1.10 oz
Aluminum Barrel Nut
SKU: 2A-ALBN-1
$29.00 Regular Price
$27.55Sale Price