Sturdy and durable design.
No calibration needed.
Special design to avoid the accumulation of material on probe.
High / Low fail safe modes.
Field-operatable in sensitivity adjustment to fit versatile density of material.
Solid Level Detection.
Powders: 
Powdered milk, flour, spices, coffee beans, coffee powder, tea, salt, sugar, grains, chocolate Tobacco, powdered cellulose, powdered clay, polystyrene powder, dry soot, soda ash, coal ash
Granular & plastics:
Gravel, glass fine power, granular plastics, foundry sand, cements, plastic pellets  Chip or pellet like:
Frozen potato chips, beans, peanuts, sweets and candy, animal / pet food Wood shavings, chalk, steering chips, styrofoams, charcoals