What can a 4.5-inch angle grinder do?

It cuts metal, rebar and bolts with a cutoff wheel, grinds welds and rust with a grinding disc, and cuts tile or masonry with a diamond blade. It is a general-purpose tool, not a precision cutter.

Should I buy 4.5-inch or 5-inch?

A 4.5-inch grinder is lighter and easier to control, and wheels are easy to find. A 5-inch model removes material faster and reaches deeper cuts, but weighs more.

It takes 4.5-inch (115 mm) wheels with a 7/8-inch arbor. Match the wheel type to the job: cutoff, grinding, flap disc or diamond.

Does it need a special power supply?

Most small angle grinders run on standard household AC power. Check the tool's amperage and use an outlet and extension cord rated for it.

Is it safe for a beginner?

It can be, with eye and ear protection, a mounted guard and a firm two-hand grip. Never remove the guard, and let the wheel stop before setting the tool down.