I had a deaver 10 pack in the back of my truck and it came out about 4 weeks later. A 12 pack might work better but they have almost no hauling load above 500lbs. I switched to the OME daker leafs and I love them, good flex and great hauling. I tow a 500lb quad and a 4500lb travel trailer in the summertime and the sag is minimal now. before I couldn't put the trailer on the back of the truck because it sank to about 1/2 inch away from the bump stops with the deaver pack.