4-part phenolic socket for medium-based ("regular") light bulbs with threads and screw-ring to hold lampshade or glass in place. 2 dark brown shells screw together and interior socket is off/on pull-chain that works with a regular light bulb. This measures 2 7/8" tall with 1/2" bottom hole that works with standard 1/4 IPS pipe. Rated 250W-250V. We combine with other items to save shipping. $4.86 each. Large hole. Shipping is $3.38 plus $.42 for each additional piece. Combined shipping- to get cheapest shipping costs (when buying different items)please buy what you need (WITHOUT SHOPPING CART) and “request invoice” (BEFORE YOU PAY) so we can send invoice with lower shipping costs. SHOPPING CART DOES NOT SEEM TO WORK FOR COMBINED SHIPPING.