This is a heavy ARCA rail specifically designed to fit a Seekins SP10. I have found it also fits nicely on a 15" Aero Precision M4E1. It is useful for putting a lot of weight on the front of the rifle. This added forward weight greatly improves balance and mitigates recoil. It does not have the machined in Mlok engagements, allowing it to be slid fore and aft fitting a wider variety of handguards. The 7 screws  have proved sufficient to hold it in place without the need for the positive MLok engagements.  The prototype of this rail was used by the PRS Midwest Regional Gas Gun Champion to secure that victory.   
 
Specifications
Length: 14.88 in.
Width: 1.9 in.
Height: 0.58 in.
Weight: 4lbs 3oz
Color: Cerakote Armor Black
 
BLEM Notes: This one has some slight burrs around the top of the holes that were not removed by blasting, and the surface on the bottom shows some slight machine marks.