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)
Howsafe 3M™ E-A-Rsoft™ Yellow Neons Ear Plugs
3M Ear Plugs, 1100 Uncorded Bullet Soft Foam, NRR 29, 1 Pair
3M™ E-A-R™ Classic Soft™ Ear Plugs
Earplugs 3M 1100 (7100100637) - Świat Zatyczek
3M1120 Comfort Soft Foam Earplugs
3M 312-1261 (70071515046) Single Pack E.A.R Soft FX 26dB
3M 1110 Corded Ear Plugs (100 Pairs) - Litelines
3M E-A-R Soft FX Corded Ear Plugs (200 Pairs)
3M 1270 Ear Plug Corded, Extra Soft, Reusable Earbuds Noise