The London Lounge

Though sweaters are wonderful garments, I am always leery of them, maybe I don't understand them: cashmere, lambs wool, merino, etc amongst materials. Guernsey knit, etc amongst weaves. Can anyone explain the properties of each type? I am eying the zippered Guernsey pictured here: http://www.guernseyknitwear.co.uk/

I am also curious about this site: http://www.woolovers.com/Products.aspx? ... ORYCATID=0

I read a rec for this site on FNB, but the prices appear too low for the sweaters to be anything but junk, but then again, I don't understand sweaters, hence my post.