Countersunk (Flat) Head Tapping Screws with Slot
Normally, these tapping screws are made in the sizes for which weight details are given. It is not practicable to make the sizes for which dashes appear instead of length data.
Technical conditions of delivery and materiel according to DIN 267 Sheet 12.

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METRIC HEXAGON KEYS AND BITS
Standard Specification for Electric-Resistance-Welded Carbon and Alloy Steel Mechanical Tubing
ISO general purpose metric screw threads — Tolerances — Part 5: Limits of sizes for internal screw threads to mate with hot-dip galvanized external screw threads with maximum size of tolerance position h before galvanizing
Fasteners — Hexagon products — Widths across flats
Fasteners — Non-electrolytically applied zinc flake coatings
Tangential keys and Tangential Keyways for Constant Loads