A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series.
An LED driver is the power supply for an LED system, much like a ballast is to a fluorescent or HID lighting system, says Al Marble, manager - sales & market development for Philips-Advance Transformer.
An impact driver is a manual or power tool that delivers a strong, sudden rotational and downward force. In conjunction with toughened screwdriver bits and socket sets, they are often used by mechanics to loosen larger screws (bolts) and nuts that are corrosively frozen or over-torqued.