These bridges are the peak of tuning stability for anyone who needs to use their tremolo arm (whammy bar). These bridges function by clamping the strings at both the nut and the bridge saddle, to stop the slackening and tightening of the string from creating slippage at either end. This in turn can cause the string to get snagged - resulting in tuning issues.
The strings are clamped into the bridge saddles by tightening the screws on the back of the tremolo with an allen key. From there the tuning is set at the machine heads. After this the nut clamps are added to clamp the string at the nut end. A final fine tune to pitch is then done with the fine tuners on the top of the bridge for each string.