Vintage WW2 (?) Abney Level Clinometer, R.S.A. (RSA) Mk IV, with Leather Case & Cardboard Box

Good overall conditiion, some marks including on the scale but it is 80+ years old! (Please study the photos and judge the condition for yourself). Appears to be complete and functioning.

It is marked R.S.A. and B 5898 with a up arrow. (see photo.)

I believe R.S.A. stands for R S Alldridge Ltd who manufactured optics and accessories and which was formed in 1928 following the liquidation of its predecessor, Chapman & Alldridge Ltd, and was acquired by Sartory Instruments Ltd in 1949.

Comes with leather case and strap, and incredibly what appears to be the original carboard box with label which reads:

V2 VC 1090

Levels, Pocket. MKIV

​​QTY. 1

Any questions or if you require further photos please let me know.