Bath Outdoors say - We flipping love this! We have been scouring the earth for a RMHAT that will fit in a trail pack and or is light enough to travel with. The number of times we've had a dinged rear mech when we've flown with a bike or got it out of the van on a bike trip. Even though this is a Chinese brand, which we don't normally touch... it's exactly what we wanted and a nice tool. We got it in red so you won't lose it when you're packing your bike box...
ZTTO say - The Derailleur Hanger Alignment Gauge can help solve a multitude of derailleur shifting problems, most notably with index shifting systems. This tool is extremely steady in operation.
The tool threads directly into the derailleur hanger. The gauge bar holds a gauge which marks the distance to the wheel. The gauge then is rotated with the wheel to the 3, 6, 9, and 12 o'clock positions, noting any differences in measurements. The alignment of the derailleur hanger is accomplished by applying pressure to the tool's arm. The results can be checked instantly.
The gauge bar is made of high-strength aluminium alloy, hardened by heat treatment. It has a replaceable threaded tip and adjusts to fit 20" to 29" wheels, with an upgraded large inner shaft for added strength and tighter tolerances for improved accuracy. It also has improved clearance and reach to fit more frame/hanger combos, including low clearance thru-axle derailleur hangers.