You need an Arbor & Hole saw. The same Arbor can then be used for several different sizes of Hole Saw.
This type of kit comes with no instructions not even a diagram so I've done this little video.
You don't need to dismantle the Arbor. Erbauer Bought from B&Q. This Uses Arbor size 'B' you need to buy matching size B Hole Saws.
Arbauer SDS Arbor (L)150mm (Dia)40mm diy.com
Once you've fitted it once you'll never forget how to do it.
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