http://www.carhartt.com/webapp/wcs/stores/servlet/CarharttSearchCmd?storeId=10051&catalogId=10101&langId=-1&recordPerPage=24&N=0Ν=RollupKey&Ns=&Ntt=10908&Ntk=CatgroupId&Ntx=mode+matchall&Nao=0&Nty=1&prevPagename=

Carhartts are work coveralls. They come in lined and unlined versions. Heavy twill. Very popular here as workwear. The company also makes other types of work clothing, but in this context, the poster is probably talking about the lined overalls.