Here is a unique white porcelain insulartor with no makers name i can see. I have no idea of the U or M # but the piece is in excellant condition and is a heavy 5 pounder, solid as a rock. Measures approx. 5 1/2" tall and 5 1/2" across bottom. I will also show a pic of the underside. I don't know much about porcelain so i'll try asking $35.00 + shipping. I accept PayPal using Gift (family/friends mode). First email as usual.