Product Description: Cy5-PEG3-Tetrazin is a dye derivative of Cyanine 5 (Cy5) (HY-D0821) containing 3 PEG units. Cy5-PEG3-Tetrazin contains a Tetrazine group that can undergo an inverse electron demand Diels-Alder reaction (iEDDA) with molecules containing TCO groups.