I;m hearing so much on sierra retracts from this online forum, yet never heard 'em advertised or publicized anywhere-----good thing for a forum, or I'd never know...Unfortunately, I purchased The Robart retracts already. One person said the Robarts are built for greaser landings only----they wouldn't put up with anything more than a greaser landing...yett he shop selling the Nitro's says The Robarts are built for this kit, The CMP hellcat. i'm reaaly confused. Ed .... sarks757 @aol.com . (.... ??????).