Specialized Design for Improved Contact and Effort Reduction Unique Welzh V-Groove design enhances fastener contact for improved grip. Open V design reduces effort needed during use. Ensures efficient and effective performance. Exceptional Strength and Durability Manufactured from robust chrome vanadium steel. High-quality material ensures longevity and heavy-duty use. Reliable, durable construction for years of service. Sizing 8mm to 21mm range. Wide versatility for different fastening needs. 8mm - 142mm 9mm - 155mm 10mm - 164mm 11mm - 180mm 12mm - 200mm 13mm - 200mm 14mm - 213mm 15mm - 228mm 16mm - 228mm 17mm - 241mm 18mm - 258mm 19mm - 258mm 20mm - 280mm 21mm - 280mm