T9 LED Circline Light Bulb 12 inch, 16W 6000K 1920LM, 9" LED Circular Tube Light, Replacement for Fluorescent Lamp Fixture FC12T9 (Ballast Must be Removed Or Bypassed) : Amazon.co.uk: Lighting
GE T9 Cool White 4-pin Circline Fluorescent Light Bulb in the Tube Light Bulbs department at Lowes.com
Feit Electric 20-Watt 12 in. T9 G10q Type A Plug and Play Linear Circline LED Tube Light Bulb, Daylight Deluxe 6500K (4-Pack) FC12/865/LED/4 - The Home Depot