This kit includes 1x Car clip set of 4, 1x carrier lock, 1x StrapRight set of 4.

Pack-Right offers car clips or J hook accessory straps. If you don't have a luggage rack open your car doors and look for a ledge along the roof line.
The J part of the hook is about as big as the end of your finger. Most (not all) vehicles have a ledge. Some times it's a rain gutter or maybe under the weather molding.
When you tighten the straps over the car top carrier bag, the tension pulls the carrier against the roof and pulls the clips up and holds them in place. The carrier bag must be packed full and tight so gear doesn't shift and loosen the straps.
Pack-Right also offers a roof protection pad which is a good idea for this application. The pad also offers traction on the roof to help hold your gear in place.
Always test this set up before you hit the road. Every stop check the clips and straps to be sure they are tight.

This light weight lock comes with a retractable coated steel cable and three digit combination lock you set to your own numbers. The lock cable threads through handles or loops built into Pack-Right car top carriers, zIpper pulls, and around your luggage rack. You can purchase two one for each side of the bag. The locks help prevent the bad guys from simply unstrapping your car top carrier and lunch stops or gas stations. For ultimate security we do not recommend leaving your car top bag on the car overnight.

All Pack-Right carriers come with four sets of straps. They are so useful and work in so many different applications you can purchase them as an extra set of four. Each pair of straps has a loop sewn in the end for quick attachment to the luggage bar or each other to make one long tie down. They have single bar slide adjustors to change the length and strong ladder lock buckle.