quality level of the products : 1. appearance: transparent sphere, clean and round, without obvious bubble or impurity. 2. specific gravity: 2.3-2.5g/cm3 3. refractive index: (20% method of dipping) 1.5-1.55. 4. roundness: product of no.1>70%, others>80% 5. component: sio2>62%. 6. waterproof capability: to neutralize 100ml water, the 0.01m hydrochloric acid demanded is not more than 10ml. testing method: products are tested by sample testing sieves, timed testing sieve shaker, roundness. in order to maintain high quality, we also undertake self-inspection, mutual inspection, and special, inspection. packing: we use waterproof plastic weave bag lined with one layer of plastic membrane for safe package and transportation, size 650x400x80mm, weight 25kg. for exporting, we use the bag weight 1000kg.