Materials marked "++" are generally available either from stock or from distributors on short lead times and at competitive prices.
Materials marked "+" are also generally available at competitive prices; but are not as widely stocked.
Material with no marking are also available; but may have longer lead times and higher prices.
Materials marked "-" are generally special order with longer lead times and higher prices.
Catalog springs are normally as follows
Stainless Steel Srings:
302 Stainless Steel
Music wire (up to .250 diameter)
Oil Tempered or Oil tempered Chrome Silicon (Above .250diameter and up to .500)
5160 (Above .500)