Piwi-interacting RNA (piRNA), the largest class of the small RNAs, are between 26 and 31 nucleotides in length and function through interactions with piwi proteins from the Argonaute protein family (gene silencing proteins).
Short RNAs are well-known to silence TEs (transposable elements) through the RNAi (RNA interference) pathway, and Piwi-associated RNAs (piRNAs) play a crucial role in transposon silencing in the germline.