This International Standard specifies the characteristics of countersunk head grooved pins which have three equally spaced grooves impressed longitudinally on their exterior surface, with nominal diameter, d₁, from 1,4 mm to 20 mm inclusive.

The displaced material to each side of the grooves forming an expanded diameter, d₂, which is larger than the nominal diameter, d₁, will cause a non-positive locking fit when these grooved pins are forced into a drilled hole equal to the nominal diameter d₁ (see clause 4).