I had a large one that would release at nitetime, lost one to behind 125# rock. This other (through lots of advice) I took needle and thread and sewed to large rock loosley , put thread from one edge to under the rock through other edge(hardest thing I ever did, I still can't frag stuff without cringing) It has done extremely well for over two months. It is opened up LARGE. Be sure to leave it loose so it can adjust w/size.