Occupancy indication device and method
Occupancy marker
Oil level detector
Oil level indicator
Oil spill prevention apparatus
On demand useful life indicator
On-demand useful life indicator and method of making same
On-vehicle display
Operation indicator
Optical display unit for pneumatic systems
Optical temperature indicator using thermochromic semiconductors
Over temperature alarm indication apparatus
Over-temperature indicator device for freezers
Over-temperature warning device
Overheated-axle indicator device
Overheating axle warning device
Overinflation indicator for tracheal tubes
Oxygen detector sheet and oxygen detecting agent using the...