Coaming Bolster Set 4.5 x 37 x 20mm - 2-Pieces - WhiteSeaDek Coaming Bolsters are a great alternative to traditional upholstered bolsters. Durable and easy to install, these bolsters will provide years of trouble-free service thanks to their closed-cell PE/EVA construction and robust 3MTM pressure-sensitive adhesive. Each set contains two 4.5" x 37" bolsters that are 20mm thick.