Strings (tennis) be more durable than many other types of strings due to its outstanding tension retention. This may help to offset the high initial cost. The use of a dense string pattern also generally improves the longevity of natural gut. Natural gut is produced by drying fibers extracted from a part of the cow intestine called the serous membrane, or serosa, which contains collagen designed to withstand the stretching and contraction of the intestine. It is this elasticity that makes the fibers useful for tennis string. Sheep intestines have also been used for racquet strings in the past. The first natural
Trembita Musical Instrument Factory 19 instruments were made. These instruments were diatonically tuned with 34 strings, however they did not have sufficient volume and did not allow the player to play in different keys easily. Continual serial manufacture of banduras was set up in 1964. Vasyl Herasymenko developed an acceptable model instrument and also developed a serial process for the mass production of banduras. From 1964-68 some 300 experimental instruments were produced. These instruments became known as the "Lviviankas" . The first models had 58 strings which included 17 bass strings. This particular instrument differed from counterparts made at the Chernihiv Musical Instruments Factory