We can run many different types of end configurations for extension springs in wire diameter ranging from .15" - .500".
Extension springs are...
typically closed wound with an initial tension specification to provide resistance to a pulling force. This initial tension holds coils tightly together. A measure of this initial tension is that force required to begin separation of the coils. Many configurations exist for the ends of extension springs which is often a critical aspect to reduce risk of hook failure.
Marik can develop a manufacturing process based on your initial tension requirements, maximum extended length, load, as well as geometry requirements.