A kind of retractable traction band,Comprising shell,The unreeling mechanism that reel and backspring are constituted is equipped in the shell,And winding what reel and the leash that can be drawn out from the shell,The leash is equipped with stop in the position close to magnetic tape trailer,The shell is equipped with the gate channel entered and left for the leash,The gate channel is defined by two gates,And the thickness of the big what leash of width and the thickness of the small what stop,The maximum of the leash pulls out length to stop the what stop when being that the gate prevents,Whole length of the leash are prevented to be drawn out the shell and pull bad the unreeling mechanism.一種伸縮牽引帶，包含外殼，在該外殼中設有捲筒和回動彈簧構成的回捲機構，及纏繞於該捲筒而可從該外殼被拉出的牽引帶，該牽引帶在靠近帶尾的位置設有止檔，該外殼設有供該牽引帶出入的閘門通道，該閘門通道由二閘門界定而成，並且寬度大於該牽引帶的厚度而小於該止檔的厚度，該牽引帶的最大拉出長度止於該止檔為該閘門阻止時，防止該牽引帶的全部長度被拉出該外殼而扯壞該回捲機構。
