The M34 V‑belt is a wrapped (cloth‑covered) rubber V‑belt commonly used as a drive belt in industrial overlockers (sergers) and other sewing / power transmission machinery.

It typically has a top width of about 10 mm and a belt thickness of about 6 mm (for the series).
It is made of oil- and heat-resistant rubber compounds, reinforced with a polyester (or other high-tensile) cord to ensure strength, minimal elongation, and long service life
The outer cloth wrap protects the internal rubber and tensile cords, reduces friction, and helps resist wear, static, and damage.
It delivers efficient power transmission even under high speed, and is used in pulley systems of machines with smaller pulley diameters.
In sewing machine / overlocker use, the M34 size often corresponds to an internal (or nominal) belt length of about 850 mm (or ~86 cm).

V Belt Industrial Overlocker M34