The Laurin & Klement RK (originally RAF 18/50 HP) was an automobile produced by Reichenberger Automobil-Fabrik (RAF) from 1911 to 1912 and by Laurin & Klement from 1912 to 1916.
The car was fitted with a front-mounted four-cylinder engine with slide valves. The engine had a capacity of 4713 cm³ and a power output of 37 kW (50 hp). The bore was 100 mm and the stroke was 150 mm. Both axles were solid, had leaf-springs and track of 1400 mm. The wheelbase was 3400 mm. The car could reach a speed up to 90 km/h.
A total of 116 units were produced, including 31 made by RAF and 85 made by Laurin & Klement.