this is what I wore and continue to wear. I've gotten years of warmth from these sets.

GI ECWCS Gen lll Level 1 Underwear Top Sand Polartec Power dry Silkweight (Large Long) https://www.amazon.com/dp/B019ZTY4D0/ref=cm_sw_r_cp_apa_i_sXIxCb8WHGYY9

Gen III ECWCS Level 2 Grid Fleece Bottoms - SAND - Small https://www.amazon.com/dp/B071NVNQHP/ref=cm_sw_r_cp_apa_i_WYIxCbCGC0JG6