This glass wool (fiber glass) is made from fine glass fibers with diameters controlled to approximately 0.008mm (8 micron). This makes the glass pliable and easy to use. Manufactured from Code No. 9989 glass, this fiber glass contains minimal heavy metals and is suitable for use as a filtering medium. Supplied in the form of roving approximately 2 inches in diam. x 22 ft. long. Sold in quantities 1 Lb. or, 12 Lb per case.