4 Ply yarn is that bit finer and lighter weight than Dk so this is a good choice for Summer clothes and garments that are going to be extra layers. It is also considered more suitable for premature and newborn babies due to lack of bulk. It is also, in my opinion nicer to knit with, the finish is just so lovely! It does take more time but it is worth the effort. 
Sirdar Snuggly 4ply is indeed nice to work with and like the rest of the Snuggly family it is easy to wash and doesn't mind the tumble drier.

There is a beautiful range of colours from traditional pastels to a number of more  up to date shades like the soft raspberry shown in the pattern.

It comes in 50g balls except for white and cream which are available in 100g balls as well

Needle size: 3 1/4 mm

Tension / Gauge :

28 sts to 36 rows 10cm x 10cm 4" x 4"

Meterage / Yardage : 226 m / 247yds 50g Ball

Yarn Specification: 55% Nylon, 45% Acrylic