The round 305 cm size from Didak Pool's Solar Pool Cover range: a blue cover marked on the box as 'fit round pool', 3.05 m. The English name Didak puts on it is 'floating solar pool cover'.
The cover lies loose on the water surface and floats by itself; there is nothing to fasten or tension. The box shows how it works as a drawing: a sun above the water, with arrows going through the cover into the pool.
In practice it comes down to this. Roll the cover out over the water when nobody is swimming, and take it off again before going in. Out of season, store it dry.
Measure the diameter of your own pool before ordering: this size belongs to round pools of 3.05 m. Didak also carries the same cover in 4.27 m, 4.57 m and 4.88 m, and in rectangular and oval versions. The pool itself is not included; it appears in the photo only to show what the cover is for.
