Gauge glass protector
 

Nice protector, for full size engine or small loco.
Obviously the length can be changed by fitting longer or shorter rods and new glass.
Measures, 4 3/4 long, 3 3/4 across x 3 deep.
The circular openings to fit on the fittings top and bottom measure 2 1/4 dia, with 1 inch opening to pass over the fittings.
The circular opening for the gauge glass tube is 1 1/8 dia.
The thumb screw is 5/16 dia thread and 1 1/4 long.

Pictures available.

Make me an offer, it'll definitely be cheaper than buying a new one.