I have a number of collapsible lenses that I like to use on my Lumix G1 but I am paranoid about them collapsing and causing damage. So I came up with this simple safety collar made from a narrow polythene tube. For this I used the tube from "Loctite Repair Express Power Putty". I cut the tube to the length of the lens barrel and made a split down the side. This can be slipped over the lens barrel to prevent accidental collapsing. I have used this on Elmars, Summars & Industar-22s and they are almost invisible in use.