Maleimide PEG

Maleimide-(CH2)2CONH(CH2)3O-PEG-(CH2)3-NHCO-(CH2)2-Maleimide, Mw 10,000
Maleimide-(CH2)2CONH(CH2)3O-PEG-(CH2)3-NHCO-(CH2)2-Maleimide, Mw 20,000