Precimex 60,000 BTU Max Single Stage 90 Degree Regulator with POL tank connection.

POL x 3/8" Female Iron Pipe Thread

FYI 3/8" Iron Pipe thread actually measures about 5/8"
1/4" Pipe thread measures roughly 3/8"

If you need a 1/4" outlet instead of 3/8" outlet see related products for a bushing.