4arm-PEG-SC (4arm-PEG-Succinimidyl Carbonate), MW 10K is a 4-arm PEG derivative with a stable succinimidyl carbonate NHS group with a longer hydrolytic lifetime than SCM.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.