The CHKADAWA T9 22W FC8T9/CW Circular Fluorescent light bulb adopt tri-phosphor circline fluorescent lamp technology, G10q 4 Pin standard base, giving you a bright light. Average 16,000 hours lifespan working with reliable electronic or magnetic ballast. Easy to replace old round fluorescent tubes in ceiling light fixtures. Tri-phosphor T9 bulbs cut down energy consumption by 20% without sacrificing brightness fits all conventional fixtures. G10q caps, the base of this lamp is intentionally made loose. How to choose T9 circular bulbs: wattage, T9 bulb size or dimensions, 4 pin G10q socket or base. Application: circular fluorescent bulb ceiling lights in living room, bedroom, kitchen, laundry room, bathroom, sewing room, hallway, office, garage, basement. Caution: do not attempt to forcibly turn the base since the lamp will break.