The compact A19 controls come with a fixed or adjustable differential. Controls that come with an adjustable differential have an internal scale plate to indicate increments of differential.
Figure 1. Interior of an A19 with a concealable differential adjustment
A knob range adjustment and visible scale are standard. Models are available with a knob for field convertible adjustment. These models come with a snap-in plug in the cover for concealed screwdriver slot adjustment.
Remote bulb models come with a bulb mounting clip with a sheet metal screw.
The A19ACA and A19ADB controls lock out. They require you to press and release the reset before operation resumes. All other controls in the series are automatic reset.
Figure 2. Screw type cutout stop