A comb is used to achieve a greater depth of coat thickness than could be achieved with the blade alone. Hence combs can save the purchase of a more expensive blade.
Wahl combs will fit on blade sizes 8.5 and less in thickness. They will not fit on larger sizes of blade. The old design of plastic comb shown has been replaced by this combined metal/plastic comb which is of stronger construction.
Combs are more difficult to use on dogs with very heavy or curly coats.