This is a black plastic HFV Audio 8 inch subwoofer box adapter ring spacer. This adapter is for when your box cutout is to big for your 8" sub. This spacer works on box cutouts up to 8" and the ring reduces the hole size down to 7.125".
 
Remember not to over tighten screws so you don't strip out the sub mounting holes or crack the adapter. We include M3 screws for sub mounting to mount the sub to ring. You need to use wood or drywall screws to mount ring to box (not included)
 
This adapter is meant for subs approx 500 RMS we have used them with higher wattage heavier subs but keep in mind, they are plastic so If you try and use a super heavy 8" subs with a ton of wattage, they may fail over time.