It's a bear!

R-7 Radio and LM-7 Radio City Model Trombones
Bore: .485"-.500" (12.3 mm-12.7 mm)
Bell: 7" (177.8 mm)

I've grouped these two horns together because the are so similar in name and design, with the same specifcations. As is common for the era, the bell and slide serial numbers do not match; for the Radio City, they are 7 LM 82xx (bell) and LM87xx (slide) and for the Radio they are 7M 94xx (bell) and R97xx (slide - Radio models carried the special R designator rather the usual Olds bore designators). Both horns date from sometime in the mid-1930's; the Radio City being probably about a year older.

I've never seen any Olds literature on the Radio City model, but the Radio model appears in an early-mid 1930's CMI catalog and is described thusly:
Voiced especially for broadcasting bands, the tone of this model is unusually compact and cannot be shattered by even mediocre transmitting. The high register is clear as a bell, the medium register full and rich, and even the low register is surprisingly resonant for an instrument designed for a purely "tenor" voice. Rapidly becoming the prime favorite throughtout the famous radio bands.
Under "Bores", the description states:
Built in one bore only, a special straight cylindrical tubing extending well into the bell, tapering slowly to the throat. Designed especially to retain compactness of tonal quality in the upper register, couteracting the microphone's tendency to shatter and deepen the pitch. Furnished in either 7-inch bell (R-7) or 7½-inch (R-7½).

Whatever special bore the Radio model has, it seems to also be present in the Radio City model, as the tuning slides of the two horns are interchangeable. So was the whole "special straight cylindrical tubing" thing just marketing? Maybe not. It's my theory Olds' early bell-tuning models (the Self Balancing and possibly the Military) were, in essence, bell tuning versions of the original Olds Standard model, with every attempt being made to replicate the taper of the TIS bell section in so far as it was possible in a bell-tuning horn. The Radio and Radio City models marked a departure from those proportions, with a more nearly cylindrical bore extending farther into the bell section. As a side note: it seems that these more cylindrical proportions became the norm for Olds - the tuning slide of my late 1930's Super (wide tone ring) fits either of these horns.

Overall View Radio on left, Radio City on right	Bell Engraving Radio	Bell Engraving Radio City
	Braces Radio	Braces Radio City
Horns in cases, Radio on right, Radio City on left	Upper Bell Braces Radio	Upper Bell Braces and Bear Counterweight Radio City
	End Crook Radio	End Crook Radio City