The FBH850-40 from Thorlabs Inc is a Optical Filter with Wavelength 400 to 1064 nm, Center Wavelength(CWL) 850 nm, Bandwidth (FWHM) 40 nm, Blocking Wavelength 200 to 1200 nm, Filter Diameter 25 mm (1.25 Inch). More details for FBH850-40 can be seen below.