The key profile is determined by the shape of the key as viewed from its tip. Typically, lock manufacturers designed their locks to accept only keys using their key profile, though some have become rather popular and used by more than one manufacturer. Most are identified by the original manufacturer’s name. The most popular residential key profile is that of Kwikset, though others by Schlage, Yale, Arrow, Dexter, Weiser and others will often be found. Many, like Schlage, offer many different profiles, though their residential and most of their commercial locks use the same basic one. In order to rekey locks to use the same key, they must all have the same or compatible key profiles.