Rab Boulder Pull On - The Boulder Pull-On is a lightweight, highly insulating fleece pull-over using a Polartec Thermal Hi-Loft Pro® in a light weight format. The Pull-on provides fantastic warmth to weight ratio and is an ideal layering piece under your waterproof shell. The open mesh stitch of the fabric means that it is 20% warmer than standard fleece and 40% more compressible. The open nature of the fabric does mean it is susceptible to wind - but this also means that it is supremely breathable, making it the ideal fleece layering piece for year round use.