BS ISO 12257:2008

This standard BS ISO 12257:2008 Aerospace. Internal six-lobe drives. Metric series is classified in these ICS categories:

• 49.030.20 Bolts, screws, studs

This International Standard specifies the dimensions of metric internal six-lobe drives used in metric screws in nominal thread diameter range 3 mm to 20 mm.

NOTE Pending publication of an International Standard relating to limit gauges, special care is required to ensure that the dimensions and tolerances specified in this International Standard are confirmed by alternative means.