Kärcher RVF 7 Comfort

Suction in pascal, as the maker measures it. More pascal helps on carpet, but it says little about how well the robot picks grit off a hard floor.

A brush that guides hair to the side instead of letting it wind around the shaft. It saves the cutting work in homes with long hair or pets.

The side brush swings out in a corner or along a kickboard, so the dust there is swept in too. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

A sensor notices where more dirt lies, at the doormat for example, and the robot cleans that patch longer or a second time.

How the mop is built: flat pads, two spinning discs or a roller. Discs press harder on dried-on dirt, a roller rinses itself while it works.

The pad slides out along a wall or a kickboard, so the last few centimetres are mopped as well. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

The robot leaves the mop at the dock before it vacuums a carpet, so the carpet never gets wet. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

How much clean water the robot carries. It sets how long it mops before a refill, which a dock does by itself.

The dock empties the robot’s dust bin, usually after every run. You only empty the dock’s bag or bin.

The dock collects dust in a bin instead of a disposable bag. No bags to buy, but you empty it yourself.

How much the dust bag in the dock holds.

The dock washes the mop for you, so you do not rinse it by hand.

The dock dries the mop afterwards, so it does not sit there wet and start to smell.

Drying is done with warm air instead of cold. It is faster and it helps against smell.

The dock mixes detergent into the water itself, from its own bottle. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

The dock can be connected to the tap and the drain, so you never fill or empty a tank. It does need a connection nearby. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

The clean water tank in the dock, which wets the mop.

The tank that catches the dirty water from the mop. You empty this one yourself.

How the robot maps your home and follows that map. Lidar measures with a laser and works in the dark, a camera looks along and recognises more.

How the robot sees loose things on the floor, such as cables, socks or a pet accident. A camera with depth sensing sees more than a bumper that reacts on contact.

An extending leg or wheel that carries the robot over a high threshold. Without one it usually stops at about 2 cm. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

Whether the robot has a camera, and what for: to recognise obstacles, or also to show you a live picture of your home in the app.

How tall the robot is. It decides whether it fits under your sofa, bed or cabinet.

How much dust the robot holds before you empty it. It matters less with an auto-empty dock, which empties the bin after every run.

The noise in decibels, in the setting its source names: makers mostly give the standard setting, shops often the highest. 65 dB is like a vacuum at half power, 55 dB like a conversation.

The capacity of the battery. It hints at the runtime, but how much the robot draws counts just as much.

How long the robot cleans on one charge, at its quietest setting. After that it recharges and carries on where it stopped.

The year until which the maker promises security updates for the robot and its app. After that, new weaknesses in a robot on your network stay open.