@Michael - quite right, it is a teaser and works best while stationary either on the anchor or on the drift. I attach the teaser to a 10m section of 100lb mono with a snap swivel on the end. I usually let the teaser down to a depth between 3-10m depending on the depth of water I am fishing and secure the main line to the roll bar on the transom with a carabiner clip. The nice thing with the teaser below the boat is that it doesn't interfere with the baits you deploy, you just need a crew member to pull it in while you are fighting a fish to avoid tangles. The flash teaser doesn't have any hooks on it so you don't bait it in any way.
It CAN also be trolled behind the boat on a slow troll or faster troll but then I'd recommend heavier duty discs like stainless steel. Ryan Williamson from Pulsator sells a very similar flasher teaser that they pull for Marlin at 8-12 knots and he swears it works like a bomb. Again it is clipped to the 100lb mono and let out into the propwash and secured to the transom.
