For direct use in AA systems manufactured by: Varian®; GBC®; Hitachi®; Shimadzu®; Thermo Jarrell Ash® (IL); Unicam®; Seiko®; and most other suppliers. Hollow cathode lamps are designed and manufactured to achieve all of the following fundamental requirements for a spectral line source. Intense emission of resonance (ground state derived) lines. Narrow line width; for maximum sensitivity and linearity. Noise free operation. Long running life and long shelf life (5 years). Cathode materials and geometry achieve a combination of spectral purity and a suitable sputtering rate. (A high sputtering rate will give high intensity at the expense of lamp life; sensitivity and linearity).