Good soil anchor, not only for toys

I am using the ground anchor for a trampoline and for my espalier fruit in the garden.
The anchor can be screwed well and keeps well. Have secured with the anchors with now my whole trellises.

UPDATE 03-2012:
We have our ground anchor unscrewed and tested in the garden. No rust, despite moist, loamy soil. So again anchor 'purely rotated. Good zinc!

UPDATE May 2015
Still seen no rust. The anchor still hold firmly in the ground.