an online site I would recommend is www.themousefactory.com . I have known the owner, Ray McQueen and his wife Edna since the 1990s and have always found them to be extremely knowlegeable and helpful when it comes to deciding the right size feeder to give your snake. Their number is on their page, call them up and you will probably speak with Edna and she will help you get set up with the correct size to feed your snake.