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Eb Contrabass Over The Shoulder Saxhorns -tubas- can be anywhere from approx. 48" tall to 60" tall. Manufacturers actually sold normal Eb and extra large Eb Contrabass Saxhorns. Many times the largest also had 4 rotary valves. Bells can range from approx 10.5 to 12.5." Bore can widely vary.....some are high .500 to low/mid .600.
Hope that helps...

P.S. If you see a listing for Bb Bass Saxhorns, they are tenor tuba in pitch (single Bb)....there were no BBb Contrabass OTS Saxhorns ( that we know of)....

Generally they're tall but very narrow. The horn I played the longest was about 10 pounds, but I never played an OTS, just body-front, valves on the right side rotor horns. OTS horns are miserably uncomfortable to hold if you're not used to them.