Abstract: A fall arrest block 10 has a spindle on which a length of lifeline 14 is wound. In normal use, the lifeline (preferably webbing) retracts onto and extends from a drum housing 12, as the workman moves towards and away from a secure point to which the housing is attached. In the event of a fall, an inertia mechanism sensitive to acceleration of the spindle operates to lock a locking mechanism to hold the spindle against further rotation. An energy absorbing link 18 is built into the webbing, close to a hook 16 to which the workman is attached. The energy absorbing link 18 includes a section of lifeline that is stretchable, but non-elastic. The locking mechanism includes a toothed ratchet wheel that is engaged by a pawl in order to lock the spindle rotation. The toothed ratchet wheel is part of a unitary body with the spindle.