This is the Hollis Silicone Replacement Neck Seal Bellow SilflexFeatures: Easy to install Can be installed on Hollis drysuits Can be Cut to Size SILICONE RUBBER has a great many variations and can be compounded to meet any number of applications. Silicone can be compounded to have tensile in the area of 1500 psi and tear up to 200 lbs ; low compression set and good resilience, moderate solvent resistance; excellent heat resistance; good release characteristics; extreme low temperature properties; and can be highly resistant to oxidation and ozone attack.