Small nucleolar RNA sR8 is a non-coding RNA belonging to the C/D box class of snoRNAs. sR8, along with other C/D box snoRNAs, performs 2′-O-methylation of ribose on a target strand of ribosomal RNA. Targeting is achieved through the C and D box components, which are short sections of conserved sequences, as well as C'/D' boxes (internal equivalents of the C and D boxes). These sequences base-pair with nucleotides in the target rRNA to direct their methylation.