SO far (and I've tried several different brands) the Rambo is the most
waterproof. If the temp is in the 30s or even the 40s, having that little bit
of mesh lining (which the Rambo has) helps prevent the 'refrigerator effect'
which can have a horse
shivering even though he's got a rainsheet on. I plan to use an antisweat
sheet underneath my unlined rainsheets when the temps get down in the 40s.
-Amy