... following products: Hand-held rock drill, YN27J Internal combustion rock drill, Air leg-rock drill, tapered drill bits, tapered drill rods, DTH hammer&DTH ... sleeves, etc.1. FeaturesThe internal combustion rock drill type YN27J is a portable rock-drilling tool, composed of a small ... petrol engine, an air compressor and a rock drill.The YN27J rock drill ...