I'm having this problem with my box of 2 12" Eclipses. I put a piece of velcro on the front corners of the box to stop sliding, but this only made it stick to the carpet, and now the carpet slides with the subs on that board over my spare tire. I work at Home Depot so I asked a couple of the guys for solutions and I got 2 answers. 1 was to put 2 "L" brackets in front of the box at the ends, and drill through the carpet and wood layer below(the box is pushed as far back against the seats as I could, so it can't move back. This would prevents it from coming forward - towards rear bumper). Another was to take out the carpet and turn it upside down. Then get some silicon and spread some beads around in a somewhat organized fashion. Set it out overnight to dry and when you flip it over, the beads of silicon should help grip the carpet to the board beneath. Don't spread the silicon, leave it in a bead form. I might try both so my subs won't move an inch. Thought this might help any of you with the same problem.