Buy on Amazon.co.uk : http://www.amazon.co.uk/gp/product/B00N7E44PI?tag=animalisimo04-21

Emintribe Men's Comfortable Cotton Spandex Fitness Yoga Pant Long Trousers (Black L)

Comfortable lightweight
100 cotton
Wide elastic waistband for add comfort
Perfect as loungewear or yoga wear Pair with your favorite comfy tee
Relaxed styling provides a comfortable and casual fit