Redkey R10

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.

The filter the exhaust air passes through. A HEPA filter holds back fine dust and pollen, which counts if someone at home has an allergy.

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. On this model: seen on the product photo, not stated in the maker's text.

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.

How long the maker says a dust bag lasts with daily use. With pets or a lot of carpet it is shorter.

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.

The highest threshold the robot takes, as the maker states it. Measure your own: the step into a bathroom or onto a balcony is often higher.

How you keep the robot out of a place: a zone you draw in the app, a virtual wall or a magnetic strip on the floor.

When the battery runs low in the middle of a run, the robot recharges and then carries on where it stopped.

Sensors under the robot that see a drop, so it stops at the top of a staircase instead of falling down it.

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

How wide the robot is. Narrower gets between chair legs more easily, wider usually means a bigger dust bin.

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 while cleaning, 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. Emptying by the dock is louder and listed on its own.

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

How long an empty battery takes to charge fully in the dock.

Matter is the standard that lets devices from different makers work together. With it you can run the robot outside the maker’s own app.

Which voice assistants the robot works with, such as Google Assistant or Alexa.

The warranty the maker gives in Germany. Consumer law here stands apart from it and can last longer.

You set days and times, and the robot starts by itself, also when you are not at home.