Product Description: Cy3-PEG2-TCO4 is a dye derivative of Cyanine 3 (Cy3) (HY-D0822) containing 2 PEG units. Cy3-PEG2-TCO4 can use its own TCO group to perform the inverse electron demand Diels-Alder reaction (iEDDA) with molecules with Tetrazine groups.