One top brand that manufactures this accessory is Knit Pro, and this particular manufacturer supplies it chart keeper to retailers around the world, making it easy to get hold of. Knit Pro also has a number of other accessories that knitters might find useful, ranging from sock blockers to needle sizer.
Yarn: Premature babies have very delicate skin and can often be allergic to wool; therefore it is best to steer clear of garments made with a wool mix. Acrylic yarn is more appropriate when knitting for preemies. Ideal yarn to use for preemie knits is baby double knit or 4ply yarn. Most preemie patterns will use these.
First and foremost it will be a great way to spend some quality time with your son or daughter. (Yes boys can work with yarn too!)
Size: Don’t put too much importance on trying to perfect the size of a preemie item of clothing. There is a great difference between premature baby sizes and so an item of any size should be suitable for at least one baby. As a general guide premature babies head circumference is roughly the same as their chest circumference. The average premature babies chest measurements are 8”-14”. However clothes of all sizes are needed for preemies, so no matter how big or small your item is it will most likely fit at least one baby.
Other types of stitch markers on the market today can be clipped onto you project when needed, and then clipped as required. These allow the individual who is working on the pattern to come back to a certain place in the design later in the project, leading to a great deal of precision in the creation of the project.