The head of the dead blow hammer can be solid or hollow (often partially filled with loose steel shot), which distributes the energy of the strike over a longer period of time and reduces rebound. If a filled hammer head breaks while in use, it is likely to scatter a spray of the loose filler particles in the vicinity. Therefore, use of a traditional hollow dead blow hammer may be restricted in certain settings, such as a manufacturing clean room, where contamination by foreign material could occur.