Here are 3 types of reversal indicator. First one is a scalper that is good at picking very short term tops/bottoms. Second tries to find when trends are weakening or exhausting and the third uses a different method (Williams Percent Range) to determine overbought/oversold conditions. All basically trying to do the same thing in different ways. Use with some kind of filter (ie something which helps you ignore sell signals in an up trend and vice versa) and these can be quite effective.