"A ball-peen or ball pein hammer, also known as a machinist´s hammer, is a type of peening hammer used in metalworking. It has two heads, one flat and the other, called the peen, rounded. It is distinguished from a cross-peen hammer, diagonal-peen hammer, point-peen hammer, or chisel-peen hammer by having a hemispherical peen." - (en.wikipedia.org 22.02.2022)
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