Posted 1 year ago
This is a basic Keuffel & Esser Co. Site level from the 1930's. It has a bubble vial on the end and inside is a diamond shaped mirror at a slant.
When you look thru the peephole, there is a brass piece at the end and the mirror reflects the bubble to show your site is level. I actually used this recently to install the fence in my yard. Made in the USA and still works like new 80 years later. The product number is 5703. UPDATE - Found this item listed in the 1913 K&E price list and the 1921 catalog.