m PEG Amine, HCl Salt, MW 3K with a reactive primary amine group (NH2) attached to the end are high-quality PEG reagents, and the use of MPEG-amines instead of MPEG-alcohols improves the physiological stability of MPEG-drug conjugates ( e.g. amide instead of ester bond).
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.