SUGGESTION: Placing a very small drop of Super Glue on the end of the shaft before inserting it into the tubing enhances the ability of the shaft fitting securely inside the tubing. Never coat the entire shaft with glue, as it acts as an insulator and current will not get directly to the tip.NOTE: You are making this insert at your own risk. Because you the buyer, are constructing this insert yourself, we will not and cannot be held liable for any damage, liability or injury caused by constructing or using it.