British fitness influencer Stef Williams has announced the launch of her own activewear brand SEFI, 'devised, designed and produced over 18 months' to create the 'most comfortable, form-fitting seamless outfits'.

The WeGLOW app founder took to social media to announce the launch, posting 'Finally I can start to share @thisissefi with you all 🤍 From designing this collection to the styling & creative direction, I’ve enjoyed every step & I am beyond excited to finally start to share the SEFI journey with you all. Thank you for the support already 🥺🤍'.