Osram Vialox NAV-T 400W E40

The cap/base of a bulb is the part that connects it to the socket in the fixture. E27 (Edison screw) and E24 (small Edison screw) caps/bases are among the most popular, although this depends on your location. GU10 is generally the most common cap/base for spotlights. Check which cap/base you need carefully as many other types are also available.

The colour rendering index (CRI) indicates how accurately colours are represented under a beam of light. The index goes from 1 to 99, with a CRI of 1 being the poorest and a CRI of 99 being the best possible. Be careful not to confuse colour rendering with colour temperature (K).