When trimer modified oligonucleotides require machine synthesis, a machine validation is performed prior to starting the job. This validation ensures that all aspects of the synthesizer are functioning properly and decreases the chance of synthesis failure. Since the trimer mix amidite is an expensive modification we take all necessary precautions to limit the chance of a synthesizer malfunction which could waste trimer mix amidite. A machine validation charge is required for each new synthesis run so it is beneficial to order all of your trimer modified oligonucleotides at once. This allows us to split the validation charge across all oligonucleotides in the order, reducing cost per oligonucleotide.