The resin contains 5-10% non cleavable covalently attached ligands, 40-45% linker for peptide acid released by 5% TFA treatment and 40 - 45% linker for peptide acid released by 95% TFA treatment. The peptide, liberated by 5% TFA treatment must be separated from the resin and deprotected with 95% TFA in a follow up step. This resin type is specially suited for effective library screening.