Roller ginning provided the first mechanical means of separating cotton lint from seed. The first true roller gin was the Churka gin, which produced up to 2.3 kg (5.0 lb) of lint/day. In 1840, the McCarthy gin was invented to gin extra-long-staple (ELS) cotton. Although the ginning capacity of the McCarthy gin was a major improvement over the Churka gin, capacity was limited to about 18 kg (40 lb) of lint per hour. In the late 1950s and early 1960s, a rotary-knife roller gin was developed. The rotary-knife roller gin had a ginning rate 12 times higher than the McCarthy gin, though the rotary knife gin still processed cotton at only about one-fifth the rate of a saw gin with an equivalent width. Around 2005, commercial development of a high-speed rotary-knife roller gin was accomplished. The high-speed roller gin processes cotton at approximately the same rate per unit width as a saw gin. The high-speed roller gin not only allows ELS cotton (such as Pima) to be ginned more efficiently, but also permits high-quality Upland cotton to be roller ginned at a rate more comparable with the saw gin while achieving the benefits of better fiber quality resulting from roller ginning. Although variations of the McCarthy gin are used today in many countries to gin ELS cottons, the rotary-knife roller gin is the only type of roller gin used in the U.S.