CRT-AS Sulfur-Resistant Thin Film Chip Resistors Bourns CRT-AS Sulfur-Resistant Thin Film Precision Chip Resistors operate in harsh environments exposed to high levels of sulfur contamination. Applications include industrial, automation, power supply, and communication base station. Bourns CRT-AS surface mount resistors are offered in four footprints from 0402 (1005 Metric) up to 1206 (3015 Metric). These Bourns resistors offer ultra tight tolerances (0.1% to 1%) and are available in a wide impedance range.