What are the conditions for a slaughtering knife, and must its handle have three rivets?

The lawful instrument for slaughter is anything that causes blood to flow, with the exception of teeth and fingernails, based on the Prophet's (peace be upon him) saying: "Whatever causes blood to flow, and Allah's name is mentioned upon it, then eat, except for teeth and fingernails. I will tell you why: as for the tooth, it is a bone, and as for the fingernail, it is the knife of the Ethiopians." Therefore, slaughtering with a knife is permissible without stipulating a specific number of rivets in its handle.