Coloplast Simpla S4 Bedside Drainage Bag / Urinary Collection Bag. The Simpla S4 2-Litre Urine Drainage Bag is the leading urine drainage bag with slide action outlet tap. For direct connection to a urinary catheter or sheath. These bags are suitable for night time use for the collection of urine. The drainage bags have an in-use life of approximately 5–7 days.