CAS 273-21-2 appears in our catalog under these names: 4–Azabenzimidazole, 4-Azabenzimidazole/ 99%, 4-Azabenzimidazole, 98% , 4-Azabenzimidazole 97%, 4-AZABENZIMIDAZOLE, 99%. Offered by: GLPBio, Chemat, Thermo Scientific (Alfa Aesar), Ambeed, Sigma-Aldrich. Available pack sizes: 1g, 25g, 5g, 250mg, 10g.