What is LowG tuning?
The ukulele is an instrument of the family of re-entrant tunings. This means that the first string on the top is sharper than the next string. Normally the G (fourth string) is sharper than the C (third string).
Although, this determines the sound of the ukulele and generates a new way of playing (especially arpeggios), it is not to the liking of all musicians. Since many of them are accustomed to the tuning of the guitar, where it goes from treble to bass.
For them, lowG tuning has been invented, where the fourth string is tuned an octave lower than normal. Normally you have to mount a twisted rope. But the twisted strings sound different from the nylon / nylgut strings. Aquila developed the Red Series ropes to replace a twisted rope. Now, with this solution you can have the four strings of the same material and texture.
Why are the strings closed?
To increase the mass per cm of length, since the metallic wound is heavier than the casing or nylon.
What does the metallic wound have to do with the Aquila Red Series strings?
That the Aquila Red Series ukulele strings carry the wound inside, because they have copper particles inside the strings. In this way you get a higher density (weight per cm of rope) without having to twist the strings. Not only is it cheaper, but the noise of rubbing the fingers with the rope is avoided.
Red Series are strings with a smaller diameter and a slightly higher tension than normal strings. The ukuleles projects the sound better from these strings and the tuning is improved since they have a lower elasticity.