These siRNA collections enable medium and high throughput analysis of phenotypes resulting from inhibition of large sets of targets from specific functional classes. • Ready-to-ship collections of Silencer Select siRNAs to popular human gene classes • Three individual siRNAs per target provided in a convenient 384-well format • Designed with an all new algorithm that yields better, more consistent knockdown • Novel chemical modifications reduce off-target effects by up to 90% • Up to 100 fold more potent than currently available siRNAs • Demonstrated improvements in consistency and reliability of phenotypic results