A rotary hammer is the bigger sibling to the hammer drill. Typically they are designed to have a hammer mode, a drill mode, and a hammer and drill mode.
Rotary hammers are great for drilling through or breaking up really hard material, In order to do this they use a chuck system that allows the bit to slide forward and backward.
This chuck system is called SDS which stands for Slotted Drive System. The SDS chuck system was the original developed by Bosch. There are two sizes SDS/ SDS Plus ( 3/8" Shaft) and SDS Max (3/4" Shaft ).
The SDS and SDS Plus size is suitable for many DIY needs to create holes up to 1 3/4".
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