The 1484-A Fiber-Optic Receiver is designed specifically for looking at single-mode signals in the range of 650 to 850 nm. The GaAs PIN in this model offers better sensitivity at 850 nm than our wider 1474A InGaAs model so if you need the maximum gain around this range then the 1484-A is a better choice than the more versatile 1474-A. It has a wider wavelength range than the Multimode version.