When buying Dental Handpieces always look for the number of holes for the attachment to the unit in the air driven high speeds. In the low speeds look for the type of attachment to the motor for example the E- Type. Always ask the seller how long the hand piece has been used, has the turbine ever been replaced, do the water jets work well, has the hand piece been lubricated before autoclaving. Some of the well lubricated and maintained handpieces work as good as new ones. Look for the bur changing mechanism, push button types are more expensive. When buying used dental equipment always get onto a dental supplier's web site and check the price of of a new one. Henry Schien is one of the biggest dental retailer -http://www.henryschein.com