- Bell-shaped glasses for level gauges
- Bell-shaped glasses for luminaries
- Sight-glasses with two diameters
- Grooved sight-glasses
- Magnifying lenses
- Glass rings
- Conical sight-glasses
- Gauges with silk-screen marks
- Sight-glasses with slits
- Sight-glasses with holes
- Sight-glasses with bevel cuts
- Prisms - Coloured displays
- Sight-glasses with ladders
- Square displays
- Oblong displays