The idea is that often S&R levels are not bounced off exactly. Sometimes a bounce off support comes a bit above support, sometimes it breaks support a bit and then bounces. The idea is to create a tight band above and below the level. Now we watch price action in this whole zone, as opposed to just at the line. The size of the band... that can be researched.. It can be in ticks, or it can be in % or it can be ATR(10)/2 for example. We can research what size of bands is optimal.