A "sportswear manufacturer" refers to a company that designs and creates clothing and accessories specifically intended for sports and athletic activities. Full definition
Will Norman previously worked for sportswear manufacturer Nike where he strived to increase levels of physical activity and participation in sport. (politics.co.uk)
This baseball cap is made by my favorite sportswear manufacturer. (pinkandnavystripes.com)
Adidas is the largest sportswear manufacturer in Europe and the second biggest in the world, after Nike. (adidasoutlet.store)