This standard BS 3123:1959 Specification for spring calipers and spring dividers is classified in these ICS categories:
17.040.30 Measuring instruments
This British Standard relates to the materials, manufacture and testing of the following types of spring calipers and spring dividers.
Type A: Instruments with rectangular section legs.
Type B: Instruments with squared section legs.
Type C: Instruments with round section legs.
Three types having rectangular, square and round section legs. Material, heat treatment and hardness, dimensions and capacities, manufacture and assembly, finish, marking, testing of the instruments.