Next is the short "barrel"; this part of the instrument may be extended to fine-tune the clarinet. As the pitch of the clarinet is fairly temperature-sensitive, some instruments have interchangeable barrels whose lengths vary slightly. Additional compensation for pitch variation and tuning can be made by pulling out the barrel and thus increasing the instrument's length, particularly common in group playing in which clarinets are tuned to other instruments (such as in an orchestra or concert band). Some performers use a plastic barrel with a thumbwheel that adjusts the barrel length. On basset horns and lower clarinets, the barrel is normally replaced by a curved metal neck.