I have used them quite successfully for strawberries Andy. Although expensive, I;m on my fourth year with them. They really don't get damaged. I did do tennis balls one year on another part of the veg plot, but they didn't last the season.

For strawberries i just use canes about 2 foot high and that seems to work very well. Any higher and the structure gets a bit too heavy for the wind up here, but you might have a more sheltered spot.

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Aerodynamically the bumblebee shouldn't be able to fly, but the bumblebee doesn't know that so it goes on flying anyway.
~ Mary Kay Ash