Cats scratch upward to stretch the spine and shoulders through their full length, and to shed the worn outer layer of claw. A post has to clear your cat at full reach or the stretch gets cut short. At 65cm this one does that for most adults, which is what lets it compete with the arm of a sofa instead of standing beside it unused. Cats that go for rugs and carpet are after something different and want a flat surface, and there are several in the cat scratchers range for them.

Sisal is the surface most cats prefer. It shreds under the claw in a way they seem to enjoy and pushes back harder than carpet does. It also wears differently: a carpet covered post frays into loops, while sisal keeps its texture as it goes down. This cat rope scratcher uses natural fibre wound tight around the uprights, on an MDF base finished in soft faux fur.

Two and a half kilos sits in a base 40cm across, with the mass low and wide rather than relying on the upright for balance. Wobble is the single most common reason a cat scratch pole gets abandoned. One bad experience and most cats will not go near it again. That is why the weight sits where it does.

Stand your cat against a wall and see where the front paws land at full stretch. Most adults reach somewhere between 50 and 65cm, which is the band this one is built for. A very large cat will want more height. Kittens get on with it from a few months because they climb it rather than stretch up it, and they grow into the full height later.

Taller than your cat can reach standing up. For most adults that means 60cm or more. This one is 65cm. A Maine Coon or a large Ragdoll may want to be taller still.

Why do cats scratch vertically? Three reasons at once. It lengthens the back and shoulders, it strips off the spent outer claw casing, and it marks territory through scent glands in the pads of the feet. Scratching does not sharpen claws. What comes away is dead keratin, and the fresh claw is already sitting beneath it.

How heavy should a cat scratching post base be? Heavy enough that nothing shifts when a cat pulls hard. Around 2.5kg on a wide base covers most cats. Lighter posts rock, and a post that rocks stops being used.

Sisal vs carpet cat scratcher is the usual choice. Sisal keeps its texture as it wears, which is what a cat is after. Carpet frays into loops that give less feedback as they go.

A vertical sisal cat scratcher suits cats that work on chair sides, door frames and sofa arms. Cats that scratch lying down want something flat instead.

The best vertical cat scratcher is the one in the right place. Height and surface matter less than siting it where the scratching already happens.