The only real electrical-limit to how short a pulse can be is the total-system inductance, including that of the capacitor, wires, and lamp itself. Short-pulse flashes require that all inductance be minimized. This is typically done using special capacitors, the shortest wires available, or electrical-leads with a lot of surface area but thin cross-sections. For extremely fast systems, low-inductance axial-leads, such as copper tubing, plastic-core wires, or even hollowed electrodes, may be used to decrease the total-system inductance. Dye lasers need very short pulses and sometimes use axial flashtubes, which have an annular cross section with a large outer diameter, ring-shaped electrodes, and a hollow inner core, allowing both lower inductance and a dye cell to be placed like an axle through the center of the lamp.