With transverse and longitudinal vials.
Used as level and slope meter to measure the angle of two separate surfaces
Aluminum frame.
Magnetic bottom.
The sea level is permanently set inside the chip, zero setting is not needed when batteries are replaced.
Buttons: ON/OFF, absolute and incremental measurement, keep the reading, buzzer alarm(not for 4910-400), unit (mm/m, %, in/ft), conversion(not for 4910-400), backlight
The display flips over when the bottom faces up

Dynabrade 79054 1/8" W x 24" L 80 Grit A/Z DynaCut Belt, 50/pack
Dynabrade 94897 Re-usable Compression Fitting Ass'y (for 8mm Hose)
Dynabrade 91430 1/2" W x 12" L 120 Grit A/O DynaCut Belt, 50/pack 
