Abstract: A strap (14,15) used in a strap adjuster for a protective helmet is provided. The strap adjuster comprises a case (10) comprising a front face (11), a rear face (12) and a slot (13) therebetween. Within the slot (13) are received the ends of the two straps (14,15), each of which is slotted and defines on one side of the slot (13) a respective rack gear profiles (16,17). A control knob (18) is rotatable in the case (10) and has one or more pinion gear profiles to engage the respective rack gear profiles (16,17). Each strap (14,15) has a mid-portion comprising a plurality of thin strap portions (21) arranged side-by-side and separated by long apertures (22) in a direction transverse to the length of the strap (14,15). The apertures (22) define the thin strap portions (21) of increased flexibility, and may he at least partially out of the plane of the strap (14,15).