This is Carol Brass' lightweight "lead" horn in silver plate, with brass leadpipe and standard size bell. This is very nice example in great condition. Serial #121593
 
Key: Bb
Bore size: ML (0.460" ; 11.70 mm)
Main tuning slide style: L (Reversed)
Bell material: Y (Yellow brass), soldered wired rim
Bell size: S (# 37)
Bell thickness: T (0.016" ; 0.40 mm)
Bell diameter: 5.000" (127.00 mm)
Finish:Silver Plated
Leadpipe material: Yellow brass
Tuning slide material: Inner / Outer Yellow brass
1st tuning slide finger ring
3rd tuning slide finger ring & stop screw
 
Accessories:

Backpacker case
CarolBrass® 3C mouthpiece
Polishing cloth
Squared crook main tuning slide
User booklet