The Kärcher WD 3 P V-17/4/20* EU III is just a bit more extensive than the regular WD 3. The biggest advantage is that this version has a built-in socket. This also allows you to connect power tools to the vacuum. That's useful, because this ensures that released dust particles are quickly captured while working. The vacuum has a dust and liquid container of 17L, which makes it suitable for average jobs in and around the house. You can use the vacuum both with and without a bag. This allows you to decide for each job what works best for you. For example, bagless vacuuming is very useful when you're working with wet dirt.