i have some of the round frabil tip ups. went to the dollar store and got a magnetic cupboard door alarm. it has the double sided tape. stuck the alarm next to the flag. i tied a piece of line to the little magnet and the flag wire. flag goes up, pulls the magnet up, and the alarm goes off. i haven't caught any fish on it yet, but i've had it set in some pretty good winds, and the wind didn't move the magnet. for a buck, you can't beat the price.