It looks skinny compared to the bigger King Cleveland (basically a 1250 but with a 24" bell) I once handled, and the main tuning slide in comparison with the 1st slide better matches the junior model as I remember seeing on the H.N. White site (it's not there anymore...).
Not providing measurements is criminal. The junior should have a 5 inch collar and a (iirc) 22" bell.
F Schmidt 2103 BBb, Laskey 30G US
Wessex TE360P Bombino Eb, Perantucci PT-84S
JP274MKII Euphonium, Tucci RT-7C
Various slide things