The Uni adapt is a great way of mounting your Petzl headlamp to helmets without a clip system, such as cycling or basic climbing helmets.
Petzl says:
Four adhesive clips for mounting a Petzl headlamp on helmets that do not have clips.
Petzl's Uni Adapt is a really simple but highly effective way of attaching your Petzl head torch to a helmet that does not already have clips. It adds versatility to your current kit while saving you serious money by otherwise having to upgrade your helmet. The 4 adaptors clip onto your helmet and attach your Petzl torch in a secure way. This is great for cyclists venturing out in the dark occasionally and for use where you're wearing a helmet after dark.