This is a 4 pieces of socket adapter and reducer set. Heavy duty chrome vanadium steel construction is designed for use with drivers and wrenches. A black oxide finish makes each piece anti-corrosion and very durable. Spring-loaded ball detent keeps your sockets still and secure. Features: 1. Socket adapters are made from heavy duty chrome vanadium steel for durability and long service life. 2. The surface of each adapter is finished by electroplating and blackening, which ensures corrosion resistance. 3. Adapter body is designed with a spring-loaded ball detent and a small hole to keep your sockets still and secure. 4. There are four socket adapters of different sizes and you can use for various sockets. 5. Common size combinations multiply the range and capability of many socket set. Specifications: Material: chrome vanadium steel Surface finishing: electroplating, blackening Quantity: 4pcs Color: silver, black (Optional) Weight: Approx. 133g Size: 1/2"(square hole)--3/8"(square head) 3/8"(square hole)--1/4"(square head) 3/8"(square hole)--1/2"(square head) 1/4"(square hole)--3/8"(square head) Package Includes: 4 x Socket Reducers