Engineer's Field Book No. Size Rulings 1307 7 1/4 x 4 5/8 Level 1308 7 1/4 x 4 5/8 Field This book contains a superior 50% rag content paper having a high degree moisture resisting surface. Waterproof ink is used and it is sewed with Bing Enamel Waterproof Thread. The binding material is also waterproof. BOORUM & PEASE B&P ELIZABETH, NJ 07208 When ordering give Number and Ruling desired.