When the plastic chainguard on my Dahon Vitesse D7HG broke, I looked for an identical replacement. I couldn't find one, but saw that this year's model has a BioLogic chainguard, so I ordered one as an experiment. It was a messy, painful job to put on. Once installed, it made an irritating buzzing noise as the chain went around and had a tendency to come off, so I removed it at once. Complete waste of money.