At first there was just snags in the seatbelt webbing. We rarely used the back since I rarely have anyone seat in the back seat. But for the last couple of years since I had a daughter we had been using the back seat to place her there. At first there was snags on the seat belt webbing. And with use the last 2 years the snags had turned into the ravel edges that we had to take the seat belt out and use the straps that came with the car seats. After taking the seat belt out we found out that the metal loop where the strap retracts through was very sharp and was what caused the seat belt to snagged, frayed and unravel.