Wrench head thickness: 2.6mm to 3.8mm. All mechanics need thin wrenches occasionally to work on transmissions, gas tanks or changing a wheel on a creeper seat. Made of high strength manganese alloy steel, these wrenches are heat treated and tempered to maximize strength. Not for high torque applications. Packaged in heavy duty plastic roll pouch Sizes include: 8mm x 9mm, 10mm x 11mm, 12mm x 13mm, 14mm x 15mm, 16mm x 17mm, 18mm x 19mm, 20mm x 2lmm, 24mm x 27mm, 30mm x 32mm