Astrea strings are affordable student strings and are an upgrade on basic factory fitted strings on cheaper violins. The E string is plain steal while strings GD and A are chrome wound. These are good strings for people starting out on their violin journey as strings in the beginning are likely to break. Especially those pesky E strings!
4/4 Strings also fit # violins.
½ Strings also fit ¼ violins.
1/8 strings also fit 1/16 violins.