T-head bolts with double nib
This standard specifies M 8 to M 80 X 6 T-·head bolts with double nib. They are designed for use in attaching components to foundations or similar structures by means of T-slots, such as are specified in DIN 649, where T-head bolts with square neck are considered adequate detachable fasteners.

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M8 x 1 to M52 x 3 hexagon head bolts with fine pitch thread – Product grades A and B
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