This basic RAD system from is a good entry point to Single Rope Technique (SRT) when combined with qualified training. The set combines product form Petzl and Singing Rock.
The climber ascends the rope with a 2:1 mechanical advantage. The climber can changeover to rappel without needing to un-weight and re-install the rappel device. Use the ascender and foot loop to climb by raising the ascender as high as you can. The sit, stand, pull motion is fast and efficient. Release the ascender and engage the Grigri to descend.
IMPORTANT WARNING: This system should not be assembled or operated without proper oversight and training by a qualified work-at-height professional.