●【CARBON STEEL】Our ball plungers are made of carbon steel material, that are sturdy and durable. ●【10 PIECES】There are total 10 pieces of ball plungers in one set that you may use for many projects. ●【EASY INSTALLATION】The ball plunger is easy to install and convenient to use. ●【ESSENTIAL PARTS】The spring plungers are great parts for providing pressure and accurate positioning. ●【WIDE APPLICATION】Our spring plunger is widely applicable for mechanical devices, clamps, molds, automatic machines, etc.