Longman Dictionary of Contemporary English
shell suit
noun
EXAMPLES FROM CORPUS
▪ Even the humble sparkler can cause horrific injuries when combined with a highly flammable shell suit.
▪ He was wearing a blue and yellow shell suit top and light, almost bleached jeans.
Wiktionary
shell suit
n. A lightweight tracksuit consisting of a matching zip-front jacket and matching elasticated trousers, each having an outer nylon shell, often bearing panels and flashes of different colours, and inner cotton lining; popular in the late 1980s and early 1990s both as sportswear and as general leisurewear.