HAP, TCP, TTCP or HATCP Granules Pure hydroxyapatite granules come in six standard sizes: 10-50 m, 50-150 m, 100-300 m, 500-1000 m, 1-3 mm and 3-6 mm. They are either dense or porous. The granules are suitable for chromatography as well as bone refill and drug delivery systems research applications...