Wolff 1911 recoil springs. Often overlooked, firing pin springs and recoil springs should be changed every 5000 rounds, especially when using reduced power springs which most competitive shooters do. Remember, the 1911 in .45 ACP used a 16lb recoil spring. And the .45 is a low pressure cartridge.
7lb and 8lb variable springs work well on most properly tuned open division pistols in 9/38
9lb variable springs work well in single stack or classic division pistols in 9mm
11lb-12lb springs work well with .40S&W limited/Standard or single stack/classic pistols shooting major loads
Sold in packs that include a new firing pin spring, so you have no excuse not to change both at the same time.
Made in the USA by Wolff, the best name in gunsprings.