Specification summary of ISO 10664 as applied to torx keys (l-key and t-handle): the dimensions the standard fixes, the full size range supplied, and the related designations commonly cross-referenced.
ISO 10664 — Scope
ISO 10664 specifies the dimensional requirements for torx keys (l-key and t-handle).
Material, surface condition and any performance rating are set by separate documents specific to this part family — ISO 898-1 and ISO 898-2, which govern bolt and nut property classes, do not apply here.
Tolerance & Product Grades
Tolerances for torx keys (l-key and t-handle) are given as limits on the individual dimensions in the table rather than as a fastener product grade.
Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by ISO 10664
| Torx size | Typical mating screw | Form | Notes |
|---|---|---|---|
| T6 | M2 hexalobular screw | L-key | electronics and instrument assembly |
| T8 | M2.5 hexalobular screw | L-key | electronics and instrument assembly |
| T10 | M3 hexalobular screw | L-key or T-handle | general light assembly |
| T15 | M3.5 hexalobular screw | L-key or T-handle | general light assembly |
| T20 | M4 hexalobular screw | L-key or T-handle | general assembly |
| T25 | M5 hexalobular screw | L-key or T-handle | general assembly, decking screws |
| T27 | M5 / M6 hexalobular screw | L-key or T-handle | construction screws |
| T30 | M6 hexalobular screw | L-key or T-handle | construction and structural screws |
| T40 | M8 hexalobular screw | L-key or T-handle | heavy assembly |
| T45 | M10 hexalobular screw | L-key | heavy assembly |
| T50 | M12 hexalobular screw | L-key | heavy assembly |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Torx Keys (L-Key and T-Handle) page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
Companion Standards
ISO 10664 controls only the geometry of torx keys (l-key and t-handle). Surface finish is governed by separate finish standards (for example ISO 4042 for electroplating), and corrosion testing by ISO 9227 (neutral salt spray). Mechanical performance is set by the standards specific to this part family, not by ISO 898-1 or ISO 898-2, which apply to bolts, screws and nuts.
