Silicone over rubber.
Worm style clamps are included.
I've had some on/off issues with rubber boots easily deforming, most due to my own installation errors.
A series of limp code due to air leaks were the result. It's an annoyance that can be fixed.
As part of my Special Series on the S85-002, I documented the replacement of OEM units with these new silicone ITB boots as we wrapped up the re-assembly.
Matt / @m3_epoustouflant
Been there, done that.