These premium quality tubes feature sturdy, uniform bottoms and consistent lengths. The 10 x 75 and 12 x 75 mm sizes are suitable for cell washing procedures. · 51 expansion borosilicate glass offers excellent chemical resistance against sodium leaching, a factor common in soda lime glass products · Tubes are packed in convenient trays for ease of use on bench tops and in drawers · The 6 x 50 mm size is often referred to as a "Durham tube" · Trays are shrink-wrapped in plastic film, with tubes remaining in constant alignment for protection against in-transit breakage and contamination · No marking spot · Designed from ASTM Specification E890 · Manufactured from 51 expansion borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class B requirements