ID: 
727
Maker's Name: 
For Clyde Fuel Systems Ltd.
Where made: 
England
Dimensions: 
150 × 30 × 5 mm

Six inch plastic rule with A,B,C,and D scales, marked 'Made in England' S137 on the front.

The back is branded CLYDE FUEL SYSTEMS LTD  COMBUSTION ENGINEERS   HILLINGTON GLASGOW. S.W.2