1. Edison Screw Bases (E-Series)

• • E26 (Medium / Standard): Measures 26 mm. It is the standard North American bulb size for daily household use.
    • • Applications: Living room lamps, ceiling fans, porch lights, and standard A19 bulbs.
      • Shop E26 Sockets

  • E27 (European Medium): Measures 27 mm. It is the universal standard across Europe.
    • • Applications: European imported lamps, standard household fixtures abroad.

  • E12 (Candelabra): Measures 12 mm. Roughly the size of a penny.
    • • Applications: Chandeliers, night lights, holiday window candles, and decorative sconces.
      • Shop E12 Sockets

  • E14 (European Candelabra): Measures 14 mm.
    • • Applications: Imported decorative fixtures, chandeliers, and European home appliances.

  • E17 (Intermediate): Measures 17 mm. Roughly the size of a dime.
    • • Applications: Microwave interiors, refrigerator lighting, range hoods, and small desk lamps.

  • E39 / E40 (Mogul): Large industrial screw bases measuring 39 mm or 40 mm.
    • • Applications: Streetlights, commercial warehouses, high-bay factory lighting, and high-wattage HID parking lot lights.
      • Shop E39 Sockets

• • GU10 (Twist-and-Lock): Features two heavy ceramic pins spaced 10 mm apart that you push and twist into place.
    • • Applications: 120V household track lighting, directional art spotlights, and modern recessed kitchen cans.
      • Shop GU10 Sockets

  • GU5.3 / MR16: Low-voltage (typically 12V) needle-sharp pins spaced 5.3 mm apart.
    • • Applications: Landscape path lighting, low-voltage kitchen track lighting, and display cases.

  • G4 / G9: Miniature capsule pin bases. G4 uses needle pins (4 mm apart), while G9 utilizes looped metal wires (9 mm apart).
    • • Applications: Under-cabinet puck lights, desk vanity accents, and contemporary micro-fixtures.
      • Shop G4 Sockets

  • G13 (Medium Bi-Pin): Standard configuration for long tube lights.
    • • Applications: T8 and T12 linear fluorescent or LED shop lights inside garages and offices.

• • B22 (Bayonet Cap): Standard 22 mm locking base common in the United Kingdom and Australia.
    • • Applications: Standard general-purpose domestic lighting in the UK/Commonwealth.

  • BA15 (BA15s / BA15d): 15 mm diameter base with either a single (s) or double (d) electrical contact point on the bottom.
    • • Applications: Automotive turn signals, boat cabin lighting, heavy industrial machinery, and RV interiors.
      • Shop BA15 Sockets

• GU24: A dual-pin twist-lock base designed explicitly for self-ballasted energy-efficient bulbs.
  • • Applications: Mandated energy-efficient ceiling fixtures (often found in newer apartments and commercial properties to prevent users from reverting to incandescent bulbs).
    • Shop GU24 Sockets

• Wedge Bases: Features a flat glass or plastic base where the internal wires exit and fold over the exterior to form a contact.
  • Applications: Automotive dashboard displays, landscape tier lighting, and string deck lights.
  • Shop Wedge Base Sockets

When it comes to upgrading your home or business lighting, the A21 bulb is one of the most reliable and versatile options on the market. Known for its slightly larger size compared to the standard A19 bulb, the A21 LED bulb delivers brighter light, longer lifespan, and improved energy efficiency. Whether you’re shopping for general home lighting, office spaces, or commercial applications, the A21 LED lamp offers the perfect balance of performance and savings.

What Is an A21 Bulb?

An A21 bulb is a standard pear-shaped bulb that measures approximately 2.625 inches in diameter. It is slightly larger than the common A19 bulb, which makes it ideal for fixtures that require more light output. The A21 design works in most table lamps, floor lamps, ceiling fixtures, and outdoor enclosures.

Why Choose a Satco A21 LED Bulb?

Switching from traditional incandescent bulbs to an A21 LED bulb offers a variety of benefits:

• Satco Products: Is a leading supplier of lighting products.

• Energy Savings: Uses up to 85% less energy than incandescent lighting.

• Long Lifespan: LED technology lasts up to 25,000 hours, reducing replacement costs.

• Brightness Options: Available in soft white, daylight, and cool white to match any setting.

• Eco-Friendly: Contains no mercury and reduces your carbon footprint.

Where to Use an A21 LED Lamp

The A21 LED lamp is perfect for areas that need powerful illumination:

• Living Rooms & Bedrooms: Provides warm, welcoming light.

• Kitchens & Offices: Bright, crisp lighting for productivity.

• Outdoor Fixtures: Weather-rated options for porches and garages.

• Commercial Spaces: Durable and efficient for high-use environments.

Shop A21 LED Bulbs Today

If you’re ready to upgrade your lighting, "CLICK HERE" to explore our wide selection of A21 bulbs, A21 LED bulbs, and A21 LED lamps designed for every application. With Satco Products brand and competitive pricing, our lighting store makes it easy to brighten your space while saving on energy costs.

Halogen Basics

Halogen light bulbs operate on the same principle as standard incandescent heating the tungsten filament until it glows but from there, halogens improve upon the process.

How Halogen light bulbs works

Operation of halogen lamps is based on the ‘Halogen Cycle’. Standard incandescent lamps and halogen lamps both use tungsten filaments. However, the filament in the standard lamp evaporates over time, causing it to weaken and eventually break. The gasses inside halogen lamps allow the evaporated tungsten to find its way back to the filament and redeposit, ensuring a long life of 20,000 hours or more.

The operating temperature is a significant factor to ensure that the halogen cycle performs properly. The interior wall of the bulb must be above 250 degrees Celsius and less than 1,100 degrees Celsius. Additionally, the filament of the lamp must reach at least 2,000 degrees Celsius. To reach this temperature, the interior wall must be in close proximity to the tungsten filament.

Benefits of halogens light bulbs

Halogen lamps offer many benefits which make them an appealing alternative to standard incandescents in many applications.

Halogen lamps provide a crisp, white light. The light quantity of a halogen light bulb is greater than a standard incandescent of comparable wattage, but the quality of the light creates a higher contrast for reading and other tasks. Halogen lamps are perfect for display accent and general lighting.

Since halogens are incandescent lamps, their CRI of 100 will render colors accurately and will match the color temperate of other light sources in the 3000K range.

Compared to standard incandescent lamps, halogens offer superior lumen performance throughout the life of the lamp.

Helpful hints in using halogen light bulbs

Don't touch the glass portion of a halogen lIGHT bulb.

For the most part, halogen Light bulbs operate in much the same way as a standard light bulb does. The biggest issue to deal with is to avoid touching the actual glass capsule portion of the bulb. Human hands leave oils on the glass, which heat up when the bulb is turned on. This heating causes the glass to become fragile and to break, thus ruining the bulb. Some halogen light bulbs are constructed as a “bulb-within-a-bulb”, such as the A-line, tubular, midbreak, and BT15 models. You can touch the glass portion of these bulbs, because the actual light producing bulb is safely inside this thick outer shell.

Be careful of the heat that halogen light bulbs can release.

Halogen light bulbs burn hotter than normal ones, so if you are using the maximum watt bulb for your fixture, and the fixture has a very close fabric shade, for instance, the extra heat may actually damage the fabric or melt plastic. Use caution when using a high wattage light bulb in these cases. In general, halogen light bulbs are about 10% hotter than normal bulbs, which in some cases is just enough to cause damage.

How to clean a halogen light bulb?

While conventional incandescent lamps can be handled with bare hands, halogen light bulbs should not. Since the quartz envelope, or bulb, of the lamp reaches high temperatures, the oils and salts from skin will deteriorate and weaken the bulb.

If your hands should come in contact with the bulb, use a small amount of rubbing alcohol and a soft cloth to clean the lamp. Allow time for the bulb to dry before using.

Halogen Light Bulb - Frequently Asked Questions was provided by www.Lighting2LightBulbs.com