http://www.seatosummit.com/products/cat/1

I want to extend/drop the temp rating of my 40F marmot
minimalist sleeping bag (my TQ), and was wondering if
anyone has heard or has experience in coupling such a
system together... They make these liners from +10F all
the way to +25F as rated by the company. Looking to do
my first winter hang in the Allegheny in late December.

Holla!