Drum bags are carrying cases for the individual pieces in your drum
set. If you plan on touring, or even on moving your drums more than
about once, you will want to invest in some of these. They are handy,
because drums are a precision instrument. You may not think so to see
a drummer whaling on them, but they are sensitive to changes in their
environment.
This is especially true during transport. A set of drums
stacked in the back of a van, pickup, or semi unpadded could easily
pierce the drum heads with the bits of metal that stick out from them.
That is where a set of drum bags really comes in handy. They can protect
your drums during the incidental jostling of transport.
They also are good weather barriers. No sane drummer would
elect to leave their drum set outdoors, but it will have to go through
the great outdoors at some point to get from your basement to a stage.
If it’s raining, you don’t want that ruining your drum set.
The cost of drum bags is minimal when compared to the cost of replacing
your entire set. They really are a good investment.