Our potent and selective h5HT_2B serotonin receptor fluorescent ligand shows high affinity for 5HT_2B serotonin receptor and high selectivity over the other receptor subtypes (K_i = 56.32 nM for 5HT_2B receptor in radioligand binding assay). With a 10 µg vial which provides enough volume for 7 assays at a working concentration of 100 nM, this product is perfect for testing 5HT_2BR. It enables cell visualization in fluorescence microscopy, confocal microscopy, and high-content system experiments, and it is potentially suitable for other fluorescence-based assays.