My dad used to sell those. The patch was on one side of a metal cup, the other side had a fiber material that you would light with a match and then the metal cup would vulcanize the patch into the tube. Very good repair 60 years or so ago. Not much use for them now. Those were natural rubber tubes and patches. The rubber made great sling shots that worked really well but that goes back 60 years or so since I have seen natural rubber tubes that stretch like crazy. Now you have to buy a sling shot with surgical rubber tubes to shoot. Instead of the fun of find a tree with a "Y" and making it yourself.