My son bought one for me for Christmas. Lacking Gary LaFontaine's ability to scuba dive to watch his flies; I like the fly tester.
I do wish I had a better understanding of how to determine the "water" speed and the speed of the variable motor.
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Swing hard, in case they throw the ball where you're swinging. Duke Snider
"You must not be too greedy in catching your said game (fish), as in taking too much at one time...That could easily be the occasion of destroying your own sport and other men's also." Juliana Berners (1450)