I near mint condition this slide dream machine made by National 
It is loaded with a pick up that work with an outside box that holds the battery 
Sounds absolutely gorgeous
Description by National :
The National Resophonic company presents the National Resophonic Triolian, featuring a steel body with walnut burst finish and a single cone. Available in original style 12 fret or 14 fret necks, these guitars produce a full, rich and lush vintage tone.
The National String Instrument Corporation patented and produced the first resonator instruments in 1927, responding to the constant need for more volume. The first instruments used three small cones – the classic Tricone design. In 1928, the single-cone design was introduced as a way to cut production costs, but this met great controversy within the company.
The National Triolian was originally introduced in late 1928 and built until 1938. Originally a wood-body guitar with a single resonator cone, in 1929 the Triolian was given a steel body. For much of the first year, a Bakelite neck was used but this miracle material turned out to be unstable and was replaced with maple.
In late 1934, the neck was changed to a 14-fret design, and to accomodate this, the body was ‘shortened’ – the scale length is the same at 25 inches, so there is no difference in string tension. This 14-fret body evokes an ‘OM’ (Orchest