Type XM4 tenders entered service in November 1911, as tenders to the second batch of 2-6-6-2 Superheated Mallet type steam locomotives which were delivered to the Central South African Railways in that year.

[1][2][3] In November 1911, the Central South African Railways (CSAR) placed a second batch of five 2-6-6-2 Mallet articulated compound steam locomotives in service, built by ALCO.

These locomotives were designated Class MF on the South African Railways (SAR) in 1912.

[1][2][3] As built, the tender had a coal capacity of 10 long tons (10.2 tonnes) and a water capacity of 4,000 imperial gallons (18,200 litres), with an average maximum axle load of 12 long tons 15 hundredweight (12,950 kilograms).

[3] A number, when added after the letter code, usually indicates differences between similar tender types, such as function, wheelbase or coal bunker capacity.