Olive removers are categorised by the size of olive they remove. Some olive removers (olive pullers) can remove more than one size of olive. Olive cutters can only remove one size of olive.
Olives are categorised by the measurement of their internal diameter.
Olive cutters
8mm (0.3″) Olive cutters
If you are using olive cutters then you will need a single tool per size of olive you wish to remove. Some tools cut 8mm olives.
10mm (0.4″) Olive cutters
There are also 10mm cutters, which have blades slightly wider apart for use on 10mm olives.
15mm (0.6″) Olive cutters
Likewise, 15mm olive cutters have wider jaws still and are for use on 15mm olives.
22mm (0.9″) Olive cutters
22mm olive cutters are for use on 22mm olives.
Olive pullers
The olive puller has screw-on adaptors that make it suitable for removing both 15mm and 22mm olives.
Because 15mm and 22m copper piping is by far the most common household piping around, you are probably better off purchasing an olive puller for these sizes and then purchasing olive cuttersto deal with all the other sizes you may encounter along the way.