Why a women's model makes a difference
A men's trousers in a small size are not the same as women's trousers. The proportions differ: narrower shoulders, a higher waist, more room at the hip and chest, and a shorter back and leg length. Clothing that doesn't get these points right will pull when bending and reaching, which is exactly why people take off their workwear at the moments they need it most.
This matters even more for certified clothing: a flame-retardant coverall that's too loose gets caught on things, and a high-visibility vest that's too big hangs crooked, so the reflective bands no longer sit at the right height.
Choosing a size
Use the size chart for the specific model and measure chest, waist and hip circumference; don't convert women's sizes from men's sizes. For matching footwear, check out women's safety shoes, which have a narrower last and lower instep. If you're outfitting a team, request fit samples before placing the large order.