NEW ERA New Era 59FIFTY MLB On-Field Seattle Mariners Alternate 7(1/8) Brand new, with tags!! This is the authentic collection of MLB (Major League Baseball). On-Field uses the same materials and design as those worn by players from all MLB teams on the field. It uses high-performance materials with high breathability, sweat-wicking properties, and UV protection (UPF50+). ■59FIFTY The 59FIFTY is a representative style of New Era. It is an icon of sports and street culture, worn by athletes and influencers around the world.