Easy Breath lab coats are a medium weight 3-layer SMS material. It still offers fluid resistance with a more light weight material.

SMS provides a fluid and particulate barrier to protect the worker without sacrificing mobility and comfort. 
Garments constructed of SMS fabric are strong and durable, yet offer outstanding comfort, breath-ability, softness, and wearable. 
SMS is lightweight and resistant to tears and punctures. SMS barrier fabric is a unique Tris-laminate construction that offers a high tensile strength and toughness that is also soft, durable, and easy to work with.