3" 337 is a Kit gun
I own a 337 AirLite Ti with 3 inch bbl and the "FS HIVIZ RED" sight, product code 103054 (as per S&W box). It is a factory deal. Called A Kit Gun as in "camping kit" I suppose, NOT as in "i made et mYself".
Love my several AirLite Ti, although this is the definitely the most accurate, pegged a rodent at 80 feet with it. Stacked up next to the regular J frame bbl of 1 7/8" I wouldn't at all object to carrying the extra 1.125" of barrel carried in exchange for an extra 40 plus feet of easy accuracy. Uncle Mikes Sidekick #2 holster makes a good no nonsense fit for it.
Coincidentally, I wanted to dispense with this in order to acquire a different piece. Bought NIB and this one has yet to fire its first full box of 50, never carried regularly, always well stored. All original packing, lock and paperwork. I bought it to keep in a car lock box but never implemented that plan. That $875 is very high compared to my expectations. Let me know if you want to get your FFL acquainted with my FFL in the matter.