It is purely for keeping the two pieces of wood in the right position, if you apply a little more force it will break. Unfortunately, I ended up breaking one of the two until I realized it because no one told me, and the fact that it is Stanley does not give it quality in the end. I would have been better off buying an anonymous one for 2-3€, essentially I would be buying the same quality, so I do not consider it a value for money purchase.