Exclude unmatched reads
From Array Suite Wiki
Array Studio NGS filtering and mapping modules include an option to Exclude unmatched reads, under the Adapter Stripping section.
If enabled, each read is checked against the supplied adapter sequence, and if no match is found in the read, it is filtered out.
This is especially useful for cases such as miRNA-seq, where reads containing mature miRNA sequence will read through the miRNA and into the 3' adapter;
longer RNAs would not contain adapter sequence at the 3' end, so would be filtered out.