Nylon tennis string, 1.30mm gauge for all-around performance. - Brand: GOSEN - Model Name: OG-SHEEP MICRO SUPER 16 - Gauge: 1.30mm - Length: 1 set (enough for 17 main strings of a racket) - Material: Nylon monofilament I'm not sure when I bought it, but I purchased it in a roll and have some left over, so I'm selling it. Please understand that it has been stored at home. Thank you. ( >_< )