These types of watches were custom made in the early 20th century for pilots as a typical pocket watch is impractical while flying. 

14k yellow gold pilot's or aviator's pocket watch with wristwatch option. Has brick and bar link 14k yellow gold bracelet for attaching the pocket watch to wear as a wristwatch. Has white enamel face with black enamel Arabic numerals. Black hour, minute and sub-second hands. Has mechanical movement. Bracelet marked "WB" and holds 56 zolotniki gold purity mark. Includes original fitted leather bound presentation box. 

Technical Information
Case diameter without crown: 38 mm

Pocket watch case size approx. 10.
Total weight: 77.4 g

Bracelet measures 21.6 cm x 1.1 cm

Serial Number: 328 518
Product Year: 1913