The "tube sight" pictured is a scope, because I own one. It is made in Japan, and is 4X. The mounts are non-authentic, and virtually worthless. Real tube scopes are easily made from brass tubing, preferably in a size you can get scope mounts for. BTW scope mounts from a small airgun scope will fit the scope pictured, but you have to make the adjuster at the breech, and the windage adjustment at the muzzle.
Hungry Horse