This is what B5 Systems says :
 
 
 


Slim design provides outstanding grip and control

One of the narrowest drop-in system handguards on the market, the ergonomics of our KeyMod Handguard affords a stronger grip for superior control. Accessories are easily and securely mounted without needing to remove the handguard. The optimal placement of rail slots on the top, bottom, and sides accommodates multiple accessories without the need for offset mounts.

    Features:
    Top and bottom slots are compatible with most non-KeyMod accessories
    Durable composite construction
    Built-in stamped metal heat shield
    Fits both round and triangle handguard caps