The Chrome Power Twister from the Marcy Bruce Lee Signature Range is ideal for building upper body strength, the power twister bar will exercise your chest, back, arms and fore arms. The power twister works by squeezing the two ends of the bar together whilst the spring coil in the middle flexes it provides tension and resistance this in turn exercises the targeted muscle groups and increases your strength. We'd recommend holding the bar for 5 - 10 seconds when contracted as far as possible for the best results from the power twister.