| symbol | material | temperature range | flammability | mark | colour | norm |
|---|---|---|---|---|---|---|
 WKT (-C) | PE | from -40°C to +70°C | flammable | none | black | FIAT 91223 |
| WKT-PP (-C) | PP-mod | from -25°C to +135°C | flammable | none | black | FIAT 91223 |
 WKT-T3A (-C) | PP-mod | from -25°C to +125°C | flammable | blue stripe | black | FIAT 91223 |
 WKT-T3B (-C) | PP-mod | from -25°C to +125°C | self-extinguishing | green stripe | black | FIAT 91223 |
 RKG | HDPE | from -25°C to +105°C | flammable | none | black | ---- |
 WOG, WOG-H | PVC mod. | from -40°C to +70°C, from -25°C to +105°C | self-extinguishing | none | black | ---- |
