B4 (classification)  B4 is a blind sport classification used in a variety of sports including sailing, bowls, swimming, and cycling. Unlike other blind sport classes, it only uses visual acuity for the purpose of being classed into it. This is a medical classification for people with visual impairments. Unlike other blind sport classes, it only uses visual acuity for the purpose of being classed into it. BlindSports SA defines this classification as "This is from visual acuity above 6/60 up to and including visual acuity of 6/24 (up to 25%). No visual field is considered." USABA defines this classification as "from visual acuity above 20/200 and up to visual acuity of 20/70 and a visual field larger than 20 degrees in the best eye with the best practical eye correction." In the United States, this classification is governed by the United States Association of Blind Athletes (USABA). In New Zealand, this classification is governed by Blind Sport New Zealand. In the United Kingdom, the classification is governed by British Blind Sport (BBS), which is recognised nationally by Sport England. On a sport specific level, Blind Sailing handles national governance related to this class in the United Kingdom. BBS handles governance for blind cricket in the United Kingdom. In golf in Scotland, classification is handled by Scottish Blind Golf. Competitors in this classification are not eligible to compete in international competitions. The classification is used in national competitions in Canada, Australia, the United States and the United Kingdom. It is used in a variety of sports including sailing, bowls, swimming, and cycling. B4 cyclists compete on tandem bicycles with a guide rider. Junior IBSA blind sailing events sometimes allow for B4 competitors in international events. In blind cricket, B1, B2, B3 and B4 cricketers all play at the same time, but a maximum combined total of seven B2, B3 and B4 cricketers are allowed on the field at one time. Scottish Blind Golf gives golfers in this classification a maximum handicap of 28 for men, with the handicap for women being slightly higher. While historically the English National Association of Visually Handicapped Bowlers had included limited field of vision as a consideration for this class, it was dropped because this vision issue did not impact ability in bowls. For swimming, the classification was eligible to compete at the 2012 Blind Sporting Association Australian Swimming Championships. There is an equivalent to this classification in blind archery known as VI Open, which is open to people with visual acuity of less than 20 degrees.