A vacuum hose is the sort of part you only think about once it stops working: it links the vacuum head on the floor to the skimmer or the vacuum point, and without a sound hose the cleaning stops dead. This one from Kokido is the classic version in extruded polyethylene, blue and corrugated, with a smooth cuff at each end that slides straight onto the connection.
The size is 38 mm, or 1-1/2 inch. That is the standard pool size, which makes the hose fit just about any vacuum head, suction fitting or skimmer. Watch out with inflatable pools: those often use a coupling system of their own, and this hose will not connect to it.
Eleven metres gets you everywhere on an average garden pool, including the furthest corner, without the hose pulling taut. Kokido describes the material as light and supple, so at the end of the season you coil it up and put it away.
Handy as a replacement when your old hose starts showing cracks or drawing air, and as a spare for anyone who looks after their own pool all season.