It's some kind of silicone not rubber. They seem to work fine, but with one caveat. In particular, the small knob gaskets for the bolts don't hold in the bore nearly as well as the OEM ones. When I worked on it for a long time and put the covers back on to keep dust out of the engine, the button/bolt seals kept chipping off and falling to the floor. I ended up adding some RTV to keep them in place.
π§ Bapmic Engine Valve Cover with Gaskets & Bolts for BMW E82 E90 E70 128i 328i 528i X3 X5 Z4 (Part Number 11127552281)
9 Review
πͺ FEL-PRO VS 50569 R Valve Cover Gasket Set: Superior Performance and Durability
9 Review
π§ FEL-PRO OS 34308 R Oil Pan Gasket Set: High-quality, Leak-proof Solution for Optimal Engine Performance
9 Review
5W-40FS A3/B4
24 Review
1.5 Inch Leveling Lift Kit Compatible With 2004-2022 F150οΌLeveling Lift Kit Fit For 2004-2022 F150 2WD 4WD Forged Front Strut Spacers Raise The Front Of Your F150 By 1.5
13 Review
MICHELIN Energy XM2+ 205/65 R15 94V Summer
35 Review
ARANA C16-08568 20" Gas Lift Struts - Perfect For Trucks, RVs, And Boats - 20 Lbs Capacity - 2Pcs Set
15 Review
2 Vepagoo 10In 13Lb/58N Gas Shock Spring Strut Lift Support For Cabinet Door Truck Tool Toy Box Lid - C16-03213
13 Review