Björn Borg Core Thong. Björn Borg Core Thong is a thin, stretchy and comfortable panty. The material is fine and made of sustainably recycled material such as cotton and elastane which makes these panties flexible. The waist of the thong is medium high and is lined with a soft mesh elastic waistband. The back of the panties is minimally covered. As a nice details, a discreet lace edge runs around the leg openings and the hip is adorned with a similarly toned Björn Borg logo. Björn Borg Core Thong is a perfect thong to have at home in your base wardrobe.