E-Simpo 10PCS E26 to Gu5.3/GU4/G4/MR16 Adapter- Standard E26/E27 Edison Screw Base to MR16 GU5.3 G4 Gu4 Base Adapter Holder Converter (PBT Material) - Amazon.com
DEMASLED 5-Pack Mini Bi-pin Socket Led Light mr11 mr16 Halogen Bulbs Base lamp gu5.3 g4 gu4 gu5.3 gu6.35 gy6.35 gx5.3 gz4 - Amazon.com
ALIDE MR11 GU4 + MR16 GU5.3 Led Bulbs 2700K Warm White for Outdoor Landscape Lighting - Amazon.com
Westinghouse 20-watt Halogen MR11 Clear Lens Low Voltage GU4 Base Xenon Flood Light Bulb, (2-Pack) 0621400 - The Home Depot