Quoted from MSV website –
A high performance co-polyester string which provides superior top spin, power and durability compared to other co-polyesters.
The MSV HEPTA-TWIST is also easy on the arm and suitable for the main strings as a hybrid. The HEPTA-TWIST is a string in a heptagonal profile which is twisted in a hot thermo process. The material is similar to the one of the well-known MSV FOCUS-HEX® string. It is very much recommended for players who seek a strong top spin effect.
The Croatian ATP player Kristijan Mesaros among many others plays and cherishes the MSV HEPTA-TWIST string.
The MSV HEPTA-TWIST (1,25mm) achieves an extra ordinary satisfaction score of 94% among players of the leading tennis string community (www.stringforum.net; 41 ratings; status 10 September 2014).
My Tennis blog’s string test reinforces the excellent performance of the string. It achieves rank # 2 ahead of well know competitive brands. Video in German: http://www.my-tennis-blog.de/tennisvideos-von-densun/sandplatzspecial-saiten/
Last but not least MSV HEPTA TWIST scored best in terms of power and tension maintenance in the big test of spin strings of the German Tennis Magazin (issue October 2014).
Structure : Mono-filament
Shape : Twisted Heptagonal
Colour : White, Red , Black
Gauge : 1.25mm