Signal Electric Mfg. Co. M-110
Made in Menominee, Michigan. Telegraph key and sounder on a
mahogany finish wooden base with switch key. 4 ohm coil. Works at 3 volts.
Used by the military for training.
Listed in the 1939 Radio Shack catalog as the "Learner Set" for $2.94.
Sold as the "Sr. Learner Set" in 1920 for $5.00.
Sold as the "Learner Set" in 1941 for $5.57.
Another Signal Electric brochure listed it as "Standard Telegraph Set" for $7.65.
Here's the text from the 1941 brochure:
On city, private and short lines learners will find this instrument
easy to handle and having a clear, distinct tone.
Bar frame and key base are black enamel, the bridge is
brass, sounding bar is aluminum with black lacquered steel
sounder plate. Key lever is nickel plated. Sounder and
key are mounted on a mahogany finished wood base.