BudsGunShop.com - It says thumb safety

yes it has a manual safety Safety features include integrated trigger safety; external manual safety; neutrally balanced sear with significant engagement and strong spring tension; and hammer catch to help prevent the hammer from contacting the firing pin
unless the trigger is pulled. it has a plastic guide rod easily replaced with a gallaway spring and rod here https://gallowayprecision.com/assembled-stainless-guide-rod-for-ruger-security-9-pistols

Hi Glen and welcome. Yes, this model has a left side Manual Safety and has a plastic guide-rod. I highly recommend a metal replacement : https://gallowayprecision.com/assembled-stainless-guide-rod-for-ruger-security-9-pistols

Hi Glen, yes this model has a manual thumb safety. The guide rod is polymer.
Stay safe & have a great day!