Park Tool Frame Alignment Gauge (FAG-2)About Park Tool Frame Alignment Gauge (FAG 2) After a crash or accident, a bicycle frame may become misaligned, causing handling issues, shifting problems and wheel installation difficulties. The Park Tool Frame Alignment Gauge measures three points of contact on the frame the head tube, seat tube, and rear dropouts to ensure that it is perfectly straight. 39" (99 cm) long with an adjustable dropout indicator to fit most sizes and types of bicycles.