3M 1110 UF foam ear plugs (corded version of the 3M 1100 ear plugs) are the stiffest of the poly-urethane foam ear plugs. For those who like the feel of UF, but want the stiffness of PVC (which makes insertion easier)
3M™ Foam Earplugs 1100 Series
3M EAR Soft FX Ear Plugs (39 Decibel Noise Reduction)
3M E-A-Rsoft FX Earplugs, 312-1261, Uncord, Class 5
3M1120 Comfort Soft Foam Earplugs
PJD Safety Supplies. 3M™ E-A-R™ E-A-Rsoft™ Yellow Neons™ Earplugs
3M E.A.R SOFT YELLOW NEON EAR PLUGS BX/250
3M E-A-Rsoft Yellow Neons Corded Earplugs
3M™ E-A-Rsoft™ Yellow Neons™ Uncorded Earplugs 312-1250, SLC₈₀
3M E-A-Rsoft Ear Plugs Noise Reduction 33dB Foam Disposable
EPSS/200 - 3M E-A-R Soft FX Earplugs - Blast Spares Direct