THey are excellent, and Leo is generous with good advice. I converted my Large Leos to "breakaway" by cutting a slot in the tail and gluiing in a round nylon spacer whose hole just fits a Q-cove pin. It works just like the now defunct Q-cove breakaways, the flasher floats up the line when a king hits your lure. A couple years back I posted a thread on Bloody Deck on how to convert your Pro-troll and Gibbs regular 11inch flashers to breakaway, I'll see if I can find that thread and post a link to it.

All you need is one Q-cove harness, you can switch it from flasher to flasher. I had about 3 dozen conventional flashers and converted them all for a cost of 20 cents/flasher.

I see that Leo now has a breakaway harness for $6, gotta get a couple and give them a try. They only work with the large and medium size flashers.
Build a man a fire and he's warm for a night. Set a man on fire and he's warm for the rest of his life.