Glass; unworked, tubes, of glass having a linear coefficient of expansion not exceeding 5 x 10 (to the minus 6), (or 0.000005) per Kelvin within a temperature range of 0-300 degrees C

Glass; unworked, in balls (other than microspheres of heading no. 7018)

Glass; unworked, in rods

Glass; unworked, in tubes, of fused quartz or other fused silica

Glass; unworked, in tubes, other than of glass having a linear coefficient of expansion not exceeding 5 x 10 (to the minus 6, (or 0.000005) ) per Kelvin within a temperature range of 0-300 degrees C, not fused quartz or other fused silica