pliers are made of two levers for gripping & pliers are a kind of hand tool ->  pliers are a tool made of two levers for gripping  pliers are a tool made of two levers for gripping & gripping produces gripping force ->  pliers are a tool that can produce gripping force  pliers are a tool that can produce gripping force & a gripping force can be used to tighten a mechanical fastener -> pliers can be used to tighten a mechanical fastener