The Gibson designs were less suitable for the sounds that the Stratocaster tremolo and its derivatives made possible. They have almost always been offered as extra cost options on guitars that sold better in non-vibrato versions. As a result, some versions are rare and command high prices from restorers and collectors. Gibson encourages this trend by refusing to sell reissue units as parts, offering them only on complete guitars (a policy similar to most guitar manufacturers). Gibson was continuing to offer Vibrola units as options on many models, but also offered a few Fender-inspired tremolo arms such as the "Floyd Rose" on some "Gibson" branded guitars (Nighthawk, M3), and a wider variety through their "Kramer" and "Epiphone" brands. Kramer have always fitted Floyd Rose trems as standard and this association continues.