MCF-A is machined in 6061, with the AA surface (All Angles, or dimpled) pattern we developed for our bolt catch (ABC/R), forward assist (LDFA), ambidextrous magazine release (EMR-A).  The AA concept was not developed for aesthetics, but as a versatile surface that offers equal traction from all angles of approach (thus the AA designation).  The AA surface can hardly find a better application than hand guard rail covers, where a user's hand can have multiple angles of approach, and hold the hand guard in different ways.

The AA pattern on the MCF-A is made of two dimple sizes and depths, a series of perforations that function both as drain holes and vents,  are drilled along its length in the middle row of dimples. 

To be sure, the use of aluminum as hand guard covers is a different approach to solving the problem of handguards heating up during and after firing.  While polymer or wood insulates the user's hands from the warm/hot handguard, MCF-A insulates, and draws and dissipates heat from the handguard.