We use two different grades of Biotin. Both grades conform to USP specifications of a pharmaceutical grade biotin and both are >99% pure. MS-Biotin Probiotic, MS-Biotin Complex and MS-Biotin Boost  are refined by Multiplesupplements.com to make it easier for the high dose to be absorbed across the intestinal wall. This is our Ultra-High grade Biotin available and most popular.  It is what we recommend first and foremost.MS-High Biotin is a standard Pharmaceutical Grade and what is available by other suppliers at varying degrees of quality. It is a cheaper grade and cost.  Multiplesupplements.com provides the cheapest 100mg Pharma Grade pure Biotin Capsules.