Sourcing from redrc.net :
Much More have released some new additions to their current line of touring car tools with the introduction of a new droop gauge and chassis blocks. The blocks are 20mm in height, perfect for providing enough clearance to measure even the lowest of droop settings, while the gauge can accurately measure the setting in 0.5mm increments from -5mm to 10mm. Both the gauge and blocks are available in your Much More standard blue, black or purple and can also be used with 1/8th scale circuit cars.
Source : redrc.net