Super Kings, Speed Kings, and Battle Kings all redirect here, pending generation of their own pages.
King Size Matchbox vehicles were larger models, produced by Matchbox in the 1960s and 70s. Some were enlargements of mainline models, others appeared only as King Size models. Most or all King Size models featured moving parts (e.g. opening doors, tipping beds), something that appeared only occasionally in the mainline series. To distinguish them from mainline models, King Size model numbers featured a K- prefix.
The King Size range was introduced in 1960, and initially featured trucks and heavy equipment (e.g. construction equipment) in a scale similar to the mainline vehicles. The DAF Car Transporter, for instance, easily carries five mainline vehicles. Larger scale cars began to appear in the 1967 line-up, starting with the Mercedes Benz Ambulance, a high-roofed car-based ambulance in approximately 1:48 scale with opening doors and a removable patient on a stretcher. (The same vehicle, scaled-down, appeared in mainline series the following year (Mercedes Ambulance.))
Other cars followed, with ten in the line up for 1971, when the King Size range was separated into two new series, Super Kings (trucks, tractors etc) with numbers from K-1 through K-20, and Speed Kings (cars, bikes etc) given numbers starting at K-21.
This arrangement appeared to restrict the Super Kings to 20 models, but 1974 saw 23 of the trucks, with model numbers above 20 duplicated in the Speed Kings subseries. To correct this, Speed Kings numbers were shuffled in 1977, now starting with K-30. This solution was short-lived, however, as the Super Kings line expanded past 29 the following year, reaching 37 by 1979. In that year the Speed Kings name was discontinued and the cars, bikes etc were incorporated into the Super Kings range.
Also in 1974, Battle Kings debuted, featuring military vehicles. Perhaps to avoid compounding the problem of duplicating model numbers, these models were issued K- numbers starting at K-101. The Battle Kings name returned in the 2000s, now applied to mainline model sets with a military theme.