Test leads are used with analogue and digital multimeters to measure voltage, current and resistance – or with logic analysers and oscilloscopes to monitor circuit inputs, performance and response at varying electrical supply frequencies. BNC coaxial test leads feature miniature RF (radio frequency) plugs with quick-connect sockets and coaxial cable. BNC test leads are used for electrical testing tasks in media, CCTV and other RF applications. In contrast, test cables and sets with 4 millimetre plugs are used in general laboratory work for standard electrical connections. 4mm test leads are usually provided with new measuring tools and multimeters. Alternatively, test cables and sets with 2 millimetre plugs and thinner cables may be suitable for testing in low voltage environments or for delicate circuitry where access space is restricted. Test equipment category standards are listed from levels I to IV, usually abbreviated to CAT II, CAT III, etc. Category specifications take the danger of high-energy transients into account; the higher a CAT number, the higher the available power and possible transients will be. Cat II test leads may suffice in normal roles, though Cat III standard leads offer more resistance to voltage spikes. In addition, safety categories sometimes give specific voltage ratings; CAT III-1000 volt leads provide more protection than CAT III-600V, for instance.