The bass drum comes in a variety of sizes from 18 to 40 inches in diameter. Concert bass drums are tuned very differently from drum set bass drums or marching bass drums. Concert bass drums are usually 36 to 40 inches in diameter and are not tuned to a specific pitch. These drums are mounted on either a folding stand or a suspended stand. Muffling the drum is one of the greatest challenges to achieve the appropriate sound. Mallets include a general ball, a pair of rolling mallets, and an oval shaped beater for a sound with more fundamental. Finding the sweet spot on the drum is something players need to explore. Most concert bass drums sound best when played off-center, but tuning, size, and head type must be considered. Most batter sides are tuned slightly higher in pitch than the resonant side. Drum set bass drums can be tuned in a variety of ways depending on the style of drumming. A rock and roll bass drum would sound very different from a jazz drum set tuning. Standard size for a drum set bass drum is 22 inches in diameter, but sizes from 18 to 24 inches are common. Marching bass drums are considered tonal bass drums. They are tuned to specific pitches and will include a variety of different sizes. Many bass drum lines will muffle the drums slightly to help in articulation and tonal projection. The drums are mounted on harnesses and carried by individual players on a playing field.