DIN rail 35x7.5 mm unperforated in lengths of 4TE 72mm 6TE 108mm 8TE 144mm 10TE 180mm 12TE 216mm
with 2 5.2mm holes at the end of the rail
Tolerance +/-3mm
4HP x18mm = 72mm
4HP x 17.5mm = 70mm
We are also happy to cut the length to your specifications - at least 2 meters
Today, single-pole circuit breakers are usually 1 division unit (TE) wide. The width of a division unit is 18 mm.
The installation width of the devices should be between 17.5 and 18.0 mm according to the DIN 43880:1988-12 standard.
says Google

Division unit - A division unit (TE, English division units (DU)) is a unit of measurement for describing the width of assemblies and equipment in electrical engineering.
says Wikipedia