Silver Plate
From sideoftheroad on ebay

Quick comment on this. Note that the name engraved on the bell is "CG Conn, LTD."
It should be just "CG Conn," as this horn was built before CG Conn sold the company to Carl Greenleaf in 1915.
The horn's definitely a Wonder Improved model.
(OK, you can argue it's a New Invention model. I won't stop you.)
It's got the union label on the back of the horn and I have higher serial number instruments that aren't engraved "CG Conn, LTD."
Opinion? Conn probably had some old Wonder horns lying around and sold them when someone asked for one,
especially if they wanted something a little different. This is a high pitch bass, after all.

Make: Conn
Model: Wonder Improved
Pitch: Bb Bass
Low Pitch, A=440hz Finish: Silver
Serial Number & Date: 9787 (1906)
Keyed Range: Low Bb to Altissimo Eb
No Front Altissimo F
Bell Keys: Split
Tone Holes: Straight, soldered

Make: Conn
Model: Wonder Improved
Pitch: Bb Tenor
High Pitch, A=457hz
Finish: Silver
Serial Number & Date: 37xx (1900)
Keyed Range: Low Bb to Altissimo F
No Front Altissimo F
Bell Keys: Split
Split Octave Key
Tone Holes: Straight, soldered

Make: Conn
Model: Wonder Improved
Pitch: Curved A Soprano (prototype)
Low Pitch, A=440hz
Finish: Lacquer
Serial Number & Date: 14541 (1909)
Keyed Range: Low Bb to Altissimo F
No Front Altissimo F
Bell Keys: Split
Tone Holes: Straight, soldered

From http://www.getasax.com/