This Cassette Removal Tool is made to help you remove your cassette. It has a supporting centre pin, which reduces the chances of you aligning it at a funny angle on your cassette - which helps to not strip it. It must be with a spanner or vice as it does not have a handle. It can also be used with a 1/2" drive ratchet/wrench. This tool is small which makes it great for the travelling tool kit.
This will remove Shimano HG style cassettes - so pretty much anything that is not Campy standard. Yes, that includes SRAM cassettes. This tool can also be used to remove internally splined Shimano Centerlock caps.