The dewalt d25303dh cordless dust extraction system is ideal for dust free drilling up to 16mm in diameter and is powered by an independent motor maintaining maximum hammer performance with no decrease in durability the extractor continues to operate for two seconds after the hammer trigger is released to ensure any debris in the telescope or hose is completely removed the high quality washable hepa filter is capable of achieving 995 efficiency with dust particles as small as 03 microns maximum