This beautifl "Art-Deco" trumpet  was made by Anton Riedl, Graslitz c.1925. The name ARIGRA is an acronym of A. Riedel Grazlitz. Riedl established himself in business in 1885 as a specialist in brass instrument valves. His son Hugo joined him in 1931.  The X shaped extender in the tuning slide permits the trumpet to be played in Bb and C. The engraving on this trumpet is extraordinary. For example, I have never seen engraving on the inside of a bell (scroll down)! The valve casings as well as the bell section are octagonal and covered with intricate  engraving. It has been said that these trumpets were especially coveted for jazz venues.