US Customs Form 4457 is the one you want. It’s pretty simple, you go in with your gear, write them down on the form with serial numbers and have a customs officer verify it on your gear then stamp the form and you are good to go. You can laminate them as well so they don’t get all torn up in travel. I’ve since had a customs officer question ownership when coming back into the country, I showed them the form and it was good to go. It’s quick and painless, and can potentially save you a lot of headaches. It’s definatley worth the 10 minutes I spent at the customs office filling out forms so I thought I’d share it here to anyone reading this.