Conn 4G New Wonder Valve Trombone
Date: 1920. Owner unknown
The 4G is the Low Pitch version of the instrument, the 5G is the High Pitch model.
What Conn said in 1924:
While the slide trombone is usually considered the Trombone proper, nevertheless the valve type of this instrument enjoys great popularity. It is much less difficult to master than the slide models because proper fingering invariably gives the correct tone, while the slide must be moved to exact positions to obtain a true scale.