Features: HIGH-QUALITY CR-V STEEL MATERIAL: Forged from heat-treated chrome vanadium steel, the surface is treated by black phosphate finish, corrosion-resistant, wear-resistant, and rust-resistant. COMPLETE 20-PIECE KIT: Including 9-24 mm sockets to meet the needs of daily maintenance work. Equipped with 3'', 5'', 10'' extension bars for access to deep tapped holes. The adapter allows the sleeve to be used with a 3/8 electric wrench. 3/8' to 1/2'' SOCKET WRENCH ADAPTER: Engineered for use with 3/8''impact wrench. Its spring-loaded detent ball securely helps latch onto sockets, preventing them from being dropped. CUSTOMIZED STORAGE CASE: Designated slots in the case keep every piece in place, anti-off hole slot, lock force more firmly reduces wear and prevents rounding off at corners. The card slot in the box is printed with a size mark for quick identification. Specification: Quantity：20PCS Drive size：1/2-Inch Drive System：Metric Drive type：Deep Material：Cr-V（Chrome vanadium steel） Package size: 33*26.8*6cm/13.0*10.6*2.4in Package weight: approx. 4280g/151oz Package List: 16* Sockets(9-24mm) 3* Extension Bars(3", 5", 10") 1* Adapter 1* Storage Case 16* Sockets(9-24mm) 3* Extension Bars(3", 5", 10") 1* Adapter 1* Storage Case