The locomotives and tenders were designed by H.M. Beatty, the Chief Locomotive Superintendent of the Cape Government Railways (CGR), at the Salt River works in Cape Town.

The tender of the 9th Class had a coal capacity of 7 long tons 10 hundredweight (7.6 tonnes) and a maximum axle load of 9 long tons 11 hundredweight (9,703 kilograms), while the tender of the 10th Class had a coal capacity of 10 long tons (10.2 tonnes) and a maximum axle load of 10 long tons 18 hundredweight (11,070 kilograms).

In the SAR years, tenders were numbered for the engines they were delivered with.

[3][4] Only these two experimental locomotives were delivered new with Type XF2 tenders and were renumbered to the SAR numbers as shown.

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