Pattern has been updated. It now includes seamed and seamless versions.

A one piece singlet or undervest for infants.

Knitted in one piece from lower back, over the shoulders, to lower front. Neck is overlapped, providing higher neck coverage without the need for ties or buttons.
Seamless version starts with the yoke, then body is worked in the round.

No gauge specified as it depends on your choice of yarn and needles.