TL175 Fluke TL175 TwistGuard Test Leads. The Fluke TL175 TwistGuard™ Test Leads offer adjustable length test tips for use in different measurement environments. By simply twisting the test lead the user can change the exposed probe tip length from 19 to 4mm (0.75 in to 0.16-inch). The adjustable tip shroud meets new electrical safety requirements to reduce tip exposure while providing the versatility needed for most measurements.