In Britain scrambles are usually rated using Ashton's system of either Grade 1, 2, 3 or 3S (S for serious), with the grade being based around technical difficulty and exposure. The North Ridge of Tryfan in Snowdonia, or Striding Edge on Helvellyn in the Lake District, are classic Grade 1 scrambles. At the other end of the scale, Broad Stand on Scafell is usually considered Grade 3 or 3S. Some of the older Scottish guidebooks used a system of grades 1 to 5, leading to considerable confusion and variation over grades 1, 2 and 3 in Scotland.