... ,HIP 4.Good service tungsten carbide balls in various of sizes * High strength, high wear resistance, high ... . * They are mainly used for the sealing of valves of oil pumps in petroleum industry's sand containing wells ... of T/T, D/P, D/A, L/C, western union, paypal and etc;8/ could offer free samples ... below 0.5kgs under the condition of freight paid by customer;9/ ...