This is the newer version of the Sirius Minus Violet filter. Details and transmission curve are available at the Sirius Optics web site. There is also a review at Cloudynights.
This particular filter was included as a special custom run for Hands On Optics, thus the Hands On Optics print on the filter. If you have any doubt regarding the fact that this is a genuine Sirius Optics MV-20 filter, it can be easily confirmed with a call to either Sirius (425-803-6918) or Hands On Optics (866-726-7371).
I've only used it 2 or 3 times, it's in perfect condition, performs as promised. Case included. Retail price is $120, this one is yours for $90 which includes shipping in Conus.