About Kwangsung GM. Down The Hole Hammers from 2" to 45". DTH Bits from 2" to 60". Over Burden Drilling system. RC Hammers & Bits. Shock Absorbers. Under Reaming Systems. Hole Openers. Shock Absorbers. Concrete Mixers. Grouting Machines. Custom order, fits to drilling sites condition, Available. With world class modern facilities and well trained experts, using the best of efficient raw mterial for each items, we have been continualy renovating manufacturing technology to achive the world best class products at the most competitive terms. Don't Worry!!! We are here, working hard for you!!!