Heat-recoverable articles, especially heat-shrinkable tubular articles, having an open end are formed so that the section adjacent said open end has a lower recovery ratio than a section adjacent thereto, thereby substantially reducing the risk of splitting when the degree of recovery is high or in applications where a high degree of unrecovered strain remains after recovery about a substrate such as a supply line. A preferred article is a tubular cap which has an open end section having a first expansion ratio, an intermediate section having a second expansion ratio and a closed end section having a third expansion ratio, the second expansion ratio being greater than the first and third expansion ratios. Such a cap may be employed to seal a conduit against ingress of moisture and other contaminants. When a supply line is subsequently to be passed through the conduit the closed end may be removed and the article shrunk to grip the supply line.