valve designs would allow. Many of these new valve designs have been widely adopted by players, especially in symphony orchestras. The Thayer axial flow valve is often available on professional models from most trombone manufacturers, and the Hagmann valve particularly from European manufacturers. In terms of volume however, the standard rotary valve remains the most common valve type, as it is used for attachments on most band instruments, as well as student- and intermediate-model trombones. Some trombones have three piston or rotary valves instead of a slide; see valve trombone. Tubing F attachment tubing usually has a larger bore through the attachment than through the rest of the instrument. A typical slide bore for an orchestral tenor trombone is while the bore in the attachment is . The attachment tubing also incorporates a tuning slide to tune the valve separately from the rest of the instrument, usually long enough to lower the pitch by a semitone when fully extended (from F to E on tenor and bass trombones, to reach the missing low B). Originally, valve attachment tubing was always coiled tightly to keep within the bell section (closed wrap or traditional wrap). In the early 1980s, American instrument manufacturers began producing instruments with open wrap, around the same time that the Thayer valve began to emerge among orchestral players. Open wrap F attachment tubing is shaped in a single loop free of tight bends, resulting in a freer response and more "open" sound through the valve. In marching bands and other situations where the trombone may be more prone to damage, the confined traditional wrap is more common, since open wrap tubing protrudes behind the bell section. Tuning Some trombones are tuned using a mechanism in the slide section instead of a tuning slide in the bell section. Having the tuning slide in the bell section (the more typical setup) requires two sections of cylindrical tubing in an otherwise conical part of the instrument, which affects the tone quality. Placing the tuning mechanism in the cylindrical slide section allows the bell section to remain conical. Slides Common and popular bore sizes for trombone slides are for tenor trombones, and for bass trombones. The slide may also be built with a dual-bore configuration, in which the bore of the second leg of the slide is slightly larger than the bore of the first leg, producing a stepwise conical effect. The