Unmasked Repeats. Cylinder Display showing large tandem repeats still remaining recognizable by Skittle, in the Repeat Masked Sequence (Feb. 2009). This section of Human Chromosome Y still displays many large repeats because they were outside of the scope of the masking program settings. A) 61 bp repeat also shown in Figure 1. B) 26 bp repeat. C) A region of unique DNA and sequence masked by N's (gray). D) 55 bp repeat. E) 49 bp repeat. F) 68/81 bp repeat. The alignment on this final repeat is not very clear from the sequence but it is still visible as repeating DNA when visualized in Skittle.