DIN 261 - T-Head Bolts with Hole Standard Dimensions and Specifications Click the Button to Download DIN 261 – T-Head Bolts with Hole Standard Dimensions and Specifications in PDF Format DIN 261 PDF Steel: 4.8, 5.8, 8.8, 10.9, 12.9Stainless: A2,A4 Terminology and Measurements d – The Nominal Diameter of the Threadl – Length of Bolts – Size Hex Head Turnkeyb – Length of the Threadk – Head Heighte – The Diameter of the Circumscribed Circle