Romper pattern includes 5 sizes:

Newborn, 0-3, 3-6, 6-9 & 9-12 MONTHS.

Gauge:

24 stitches
 and 
26 
rows sc (back loop only) =
10 x 10 cm (4 x 4 inch)

Materials:
Crochet hook 3,5 mm, 5 ply/sport/12 wpi yarn (e.c. Drops «Safran», Drops “Baby Merino”160-175m/50 gr): 100-200 gr, yarn needle , scissors

Romper is crochet in one piece. Seamless.