I ended up getting 4 I Bolts, bolting 1 on each side of the tool box, and then the other 2 I bolts into the bed on wash side of the tool box an I bought the Most heavy duty chain the local hardware store sales, 6000lb chain @ $3.80/ft An got some heavy duty locks. I looked into the "Hex Chain" an its some thought stuff. It protects A Lot more against Bolt Cutters since the chain is Flat on all sides it spreads the force over a flat area making it a lot more Cut Resistant compared to regular chain which the bolt cutters apply all the cutting force to the point of contact. I was gonna get some Hex Chaim but was gonna have to order it