The number on the X-Nite filter indicates the wavelength cutoff frequency at 50% light transmission, 715nm, 780nm, 830nm, 850nm and 1000nm. The 830nm and 850nm will have similar characteristics except the 850nm is slightly more aggressive at the cutoff and has a substantially higher passband limit of 1100nm@99% versus the 830nm 900nm@99% limit passband. The limit passband is the frequency where the filter transmits at a specified higher percentage. See our controlled example shots for comparisons here.