Additional Information:“4 tiers” or brands of different quality autosampler vials to meet every Lab need:. RSA™ - Reduced Surface Activity glass for most reliable performance. Non-coated, silanol free surface. AQ™ - Compares to "Certified" Brands. Type 33 borosilicate glass. MicroSolv™ -Pharmaceutical grade, N51A borosilicate glass. BASIK™ - Economical, good quality vials