Twist counter, consisting of a pair of clamps, one of which shall be rotatable in either direction and positively con- nected to a revolution counter. The clamps shall be adjustable to permit testing yarn lengths as specified in the table. For cer- tain folded, cabled and similar yarns, it may be convenient to make provision for displacement of the non-rotatable clamp to allow for change in length of the test specimen during un twisting. Means shall be provided for applying the appropriate straightening tension (see ISO 721113) prior to clamping