I have 5 NIB Du-Bro soft mounts One is model #684. Three are model#686. The last one is model#688. If you have never used one of these they are really nice. Really quiets down the noise coming from the airframe and smooths out the engine. These were designed before all these small gas engines hit the market, But I think they would be great on a 20cc gasser. Asking $60 OBO for all 5.