An apparatus and method for straightening filaments. The apparatus includes a transport device for transporting filaments; a heating device including a heating channel forming a transport path for the filaments; and a cooling device arranged downstream of the heating device in a direction of transport, including a cooling channel that continues the transport path for the filaments. Cross-sectional areas of the heating channel and the cooling channel at least partially overlap.

The present disclosure describes a medical device assembly comprising an expandable medical device wrapped with an improved constraining sleeve. The sleeve in accordance with various embodiments of the present disclosure is thin walled and translucent, having reduced edge sharpness. The sleeve in accordance with the present disclosure exhibits resistance to ripping and delamination. Various embodiments of the present disclosure provide methods of making sheet material usable for constraining sleeves from flattened film tubes. Methods for making improved constraining sleeves and medical device assemblies that comprise an improved constraining sleeve are also disclosed herein.