This Pantheon Arms designed MLOK handguard for the AR15 provides tremendous value for your money. It is 8.5 inches long, MLOK on 7 sides, with a full length Picatinny Rail was designed especially for the Dolos takedown system, but works great with the standard barrel nut (sold separately).  The inner diameter is 1.750".
 
The difference between this handguard and those made by others is that Pantheon Arms combinse the strength of lockup provided by a threaded barrel nut with the clamping power of a compression lock. There are no jam nuts or set screws to loosen, even under the extreme torque applied to the handguard when attaching your barrel to your rifle.