Axygen's spectum color closed cap boil-proof tubes will not open during boiling.

Composed of a homopolymer, tubes have ultrasmooth conical bottoms to allow 100% visibility and no sharp 'gates' to cause cuts and scratches. Frosted side surface area for writing. Extremely accurate and visible graduation markings. Thin membrane in cap middle allows easy syringe penetration. Diamond polished molds allow tubes to be manufactured without contaminating releasing fluids.