All of these T12 bulbs have been tested and work. Most are used, but some are new, but old stock. All of these have the single pin (G13 Bi-pin Base) at each end. Most are cool white and have long lives, up to 20,000 hours. There are various makers that may include Phillips, GE, Sylvania and Alto. I have 20+/- of these bulbs. These are getting difficult to find. Compare at $24 per bulb. $10 each or best offer on the lot.