Epiphone Century Series. Recent technical innovations include Ken Parker's use of carbon fibre in high-end acoustic archtops, and the Godin Montreal hybrid guitar. Construction Archtops usually have three-a-side pegheads and necks similar in width to a steel-string acoustic rather than an electric. High-end models traditionally have "block" or "trapezoid" position markers. The top or belly (and often the back) of the archtop guitar is either carved out of a block of solid wood or heat-pressed using either a solid top or laminations, the latter being a less expensive construction method. The belly normally has two f-holes, the lower of these partly covered by a scratch plate raised above the belly so as not to dampen its vibration. The arching of the top and the f-holes are similar to the violin family, on which they were originally based. The contours of the arching profile are usually derived in an ad hoc fashion. The tops of Gibson's archtops were parallel braced. X-braced designs were introduced later, giving a tone closer to that of a flat-top guitar. Sitka spruce, European spruce, and Engelmann spruce are most often used for the resonant tops of archtop guitars, although some guitar builders use Adirondack spruce (Red spruce), or Western red cedar. Archtop guitars often have Curly maple or Quilted maple backs. Full-sized archtops are among the largest guitars ever made, with the width of the lower bout in some cases approaching 19 inches (47 cm). The original acoustic archtop guitars were designed to enhance volume, so they were constructed for use with relatively heavy strings. Even after electrification became the norm, jazz guitarists have continued to fit strings of 0.012" gauge or heavier for reasons of tone, and also prefer flatwound strings. Thinline archtops generally use standard electric guitar strings. Many vibrato systems cannot be fitted to an archtop owing to the need to cut large holes in the belly to accommodate the mechanism, with the exception of the Bigsby vibrato tailpiece and the long tailpiece versions of the Gibson Vibrola. These vibrato systems mount on the surface of the guitar and need no body routing. Other systems have been used and trialed since this time. Various use of the term "archtop" Although "archtop" normally refers to a hollow-bodied, arched top instrument, some makers of solid-bodied guitars with carved bellies also refer to these as archtop to distinguish these from flat top guitars. For example, Gibson