It is unwise and unsafe to use Safe T Sleep Sleepwrap baby wrap for more than four years. After this lifespan the fabric weave consistency cannot continue to provide a firm, wide band. This could put babies at risk, as the used; now flimsy fabric may bunch up into a narrow cord which could cause localised constriction and/or pressure around the baby's chest and tummy.
After 4 years the automatic fastening strips and fabric will eventually lose their strength, and grip and the safety may be compromised. See http://www.safetsleep.com/pages/product-knowledge
Incorrect, untested fabric and dimensions may place babies at risk.
After 4 years of use the product has provided an extremely economical and versatile life span.
Also see FAQ#4.