BD Drill - One-stop-shop for all your drilling solutions.The BD Drill range of 3" DTH hammers is designed around proven technology to perform at the top end of the performance scale compared to other tools on the market. These tools are excellent for all types of drilling applications including residential geothermal, production quarry drilling, seismic drilling and small construction drilling.Our 3" hammers are available in the popular DHD 3.5 shank with foot valve type and without foot valve type with HD35A and Mission30 bit shank for operation at higher pressures ranges from 1.0-1.5Mpa.?Features of the with foot valve type:1. More reliable air distribution.2. Simple design of the piston, durability performance.3. More efficient energy transfer, faster drilling speed, lower air consumption and lower oil consumption.4. Fewer internal parts, simple structure, longer life, less failure and easier to maintain because all the parts are heat treated.5. Easy to disassemble because the top sub, the drive chuck and the external cylinder are connected by multi-step thread.? http://www.bddrillgroup.com/dth...r/3-inch-dth-hammer.html