It is a wound a string, which is anyways rare for a on mandolin - thus it sounds more round and full than other a-strings. Anyways it is a bit darkish in sound, not very ringy, being of steel. It is polished, so no finger sound. It is extremely reliable and lasts very long. I use it since 20 years, tried many other brands but was never satisfied and always came back to thomastik. Quite pricy, but worth every penny.