This is a screw-mount for velcro cable ties (I have 12mm wide velcro straps but the slot is 16mm wide). The screw hole is designed for a #6 countersunk screw - though I widened the hole a bit so the head sits flush.  

Printed on P1S, PLA, 3 wall loops, 15% gyroid infill. Each one takes 2.36g of filament and about 5 minutes of print time. 

keywords: cable tie, mount, saddle, velcro cable strap