EDP Number: 50343
Starrett
Catalog Number: 73B-12
73B-12 Yankee Spring-Type Calipers, Inside, 12" Size and Capacity, Quick-Spring Nut, Flat Leg
https://www.starrett.com/metrology/product-detail/73B-12#:~:text=Caliper%20size%20and%20capacity%20is,size%20and%20capacity%20is%2012%22.