Girl's Day has been recently signed as endorsement models for a pharmaceutical company (Samjin Pharmaceutical).  The idols have already successfully completed the filming of the first CF. On October 10th, their company revealed, "The 5 members of Girl's Day have been contracted as models for the headache reliever 'Geworin', and have completed the filming for the TV advertisements, which will be aired starting mid-October." They continued, "Girl's Day's hit song 'Twinkle Twinkle' from earlier this year will be used as the commercial's theme song." When asked about their decision to use Girl's Day as endorsement models for 'Geworin', the #1 headache reliever in Korea, Samjin Pharmaceutical stated,"We decided to cast them because Girl's Day's fresh and active image matched well with the product." Having also been chosen as models for the luxury sports-casual apparel brand, NEPA, Girl's Day seems to be on the rise as a blue-chip in the field of endorsement models.