Top row: o-rings from the solenoid shaft on my junker HPFP. L-R: top, center, bottom ring.
Center row: new "Chemical-Resistant Viton Fluoroelastomer O-Ring, Super-Resilient" o-rings from McMaster-Carr (I only ordered top and center-shaft rings). These are the same rings I installed in my original HPFP, whose post-installation perfomance I've been reporting on in this thread.
Bottom row: new 'Chemical-Resistant Low-Temperature Fluorosilicone" o-rings from McMaster-Carr.