They are spring-loaded. I also think most spring-loaded are actually made of delrin. I'm not 100% on that. The sticky here doesn't really say what kind of detents they are. But they are not rubber & will not wear out. Honestly I don't trust rubber detents anymore.
"I'm willing to admit that I may not always be right, but I am never wrong."-Samuel Goldwyn
Minutes from Hillary Clinton's post-election powwow w/ Lucifer:
HRC: "Master, I don't understand... You said that I would win the election..."
Prince of Darkness, The: "And YOU said that you had a soul..."
FLIRG: *cackles disturbingly*