ZURN borosilicate boiler furnace inspection window .
3 inch diameter 1/4 thick glass lens reworked to 2 7/8 diameter .
a lot of hours spent turning a bit over polish and the only issue I did not like.
I removed the finish and ground the edges to reflect a flat KOPP lens good bevels on the edges which also helps avoid chipping .
This is something a purest like me who wants in a decent close runner up to an original flat semaphore lens that's difficult to find.
ZURN borosilicate boiler furnace inspection window .
3 inch diameter 1/4 thick glass lens reworked to 2 7/8 diameter .
a lot of hours spent turning a bit over polish and the only issue I did not like.
I removed the finish and ground the edges to reflect a flat KOPP lens good bevels on the edges which also helps avoid chipping .
This is something a purest like me who wants in a decent close runner up to an original flat semaphore lens that's difficult to find.