Mean Length Turn, sometimes Mean Length per Turn is the mean length of winding turn in a coil, usually referred to by the initials MLT.
The dimensions of a coil former or bobbin define the MLT of a full wound coil.
[1] In some cases the coil is not made of a single wire with multiple turns, and a coil former is not always necessary, but may be constructed in a stack of printed circuit layers.
[2] The MLT is an important measure in the design of inductors, transformers and other wound components.