1. A needleless access connector for connecting medical devices, comprising: a compressible valve, comprising: a first section with at least one concave cutout in its section； a second section that is compressible and provides volumetric displacement, the compressible valve having an axis length of 0.62 to 0.82 inches. 2. The connector according to claim 1, in which the second section has an axial length greater than the length of the first section. The connector of claim 1, wherein the second portion of the compressible valve has an annular outer surface that extends from 30% to 66% of the length along the axis of the compressible valve. The connector of claim 3, wherein the annular surface is cylindrical. The connector of claim 4, wherein the compressible valve comprises an elastic material. The connector according to claim 5, further comprising: a casing, wherein the compressible valve is located in the casing in which the first portion of the compressible valve seals the first opening of the casing. The connector according to claim 6, in which the casing further comprises: a male Luer connector at one end, and a female Luer connector at the other end. The connector according to claim 7, in which the casing contains channels configured to provide fluid flow through them when the compressible valve is compressed. The connector of claim 8, wherein the needleless connector has a length of 1.02 to 1.13 inches. The connector according to claim 9, in which the casing and the valve are combined so that the volume of fluid required to expel air from the connector is from 0.17 to 0.19 ml. The connector of claim 10, in which the casing is made of polycarbonate, polystyrene and1. Соединитель для безыгольного доступа для соединения медицинских устройств, содержащий:сжимаемый клапан, содержащий:первый участок по меньшей мере с одним вогнутым вырезом в его секции；второй участок, который является сжимаемым и обеспечивает объемное вытеснение,причем сжимаемый клапан обладает длин
