In the field of fine mechanics space conditions are often difficult, so that the correlation of a single head size to a given thread diameter fails to meet the requirements arising in applications involving small screws. To provide the widest possible range of variation whilst keeping the number of head sizes comparatively small, three different head sizes have been allocated to each nominal thread diameter, and two sizes of each set match the heads of the next larger and smaller nominal thread size respectively. Thus, for example, the medium head of the M 0.7 screw is equal in size to the large head of the M 0.6 and the small head of the H 0.8 screw.

DIN 84, which likewise deals with slotted cheese head screws, starts at thread size M 1, but only covers screws in one head size to each thread diameter. From and including M 1, the series of cheese head screws standardized in DIN 84 directly continues the B series of DIN 8243 in terms of head sizes. Therefore, this Standard contains no provisions regarding nominal sizes M 1 to M 1.4 (Series B, medium head). Moreover, from and including M 1, Series C (large head) has ceased to be needed, so that it likewise can be omitted.