i seen at our fly shop nearby (bout an hour drive) while getting some streamer & scud hooks some slip on leader loops....they are made by cortland & was a florescent yellow green in colour......slide on the fly line kinda like a chinese finger trap toy & fasten on with a length of shrink tubing.......the pack of 4 was bout 4$ so i got 1 just to try out & they work great.....easy to put on too......i ruined the first leader loop tryin to put it on so i cut an angle on the tip of a fly line & the loop went on just fine.....even stayed on when i attached a 25lb weight to the end of it & tugged it around a little like i was fightin a fish (didnt do the test with the line on my rod).......

had some by a different company 2 years ago but never would stay on the line, slipping off when ya hook a desent size fish......