Aquila's popular red series strings for concert ukulele started out only as single strings. This is a full set of four strings, all of them red. This particular set is GCEA tuning with a low G. The red comes from a copper ingredient that is mixed with the nylgut formula which allows lower frequencies to be reached than is normally possible.

These are different formula string to the single Aquila red series. The copper content is varied in each string, meaning the guage of the strings is similar on each (the variation in sound is achieved by making the strings different density, rather than making them thicker or thinner). In this way, the sound is much clearer and brighter, particularly on the lower (traditionally thicker) strings.

We should add however that the Low G string in these sets is (as it has to be to play an octave lower) thicker than the standard high G.

It is necessary when customising your Ukulele and fitting your new string, to do one of two things.

You can either use a nut file and very carefully widen the groove it will sit in.

or

As you are tightening the string to bring it to pitch, lift it out of the groove two or three times to stop it from becoming trapped, over tensioning above the nut and snapping.