TX 19 E18 Size: 16.7mm Features: -Material: Vanadium steel, polished, chrome-plated.-Hand-operated, knurled grip.-Torx: Reg. trademark of acument intellectual properties, LLC. USA.-Often used in industry, aerospace.-Drive connector square (female): 0.5".-Depth of head: 0.51" - 0.63". Specifications: -Square drive as per DIN 3120 - C 12.5, ISO 1174 with ball retaining groove. Dimensions: -Dimensions: 1.5" - 1.63" H x 0.53" - 1.02" W.