Flexible rubber, plastic, foam or other material that attaches a speaker driver’s diaphragm (the moving cone or dome – the drive unit) to the basket (the structure holding all the parts of the speaker driver in place) and allows the diaphragm to vibrate in and out. The surround, also called the suspension, holds the diaphragm or actual moving drive unit in place within the speaker driver as a whole. It is attached to the outer edge of the diaphragm at its widest point (where its diameter is the greatest) and to the corresponding widest point of the basket. he surround serves to seal the speaker driver from air when it is placed in an enclosure, hold the diaphragm in place, allow the diaphragm to move to generate sound, and help bring the diaphragm back into a resting position when there is no input signal. If the surround was not flexible, the speaker could not produce sound (the diaphragm would be locked in place). Without the surround, the diaphragm would not stay properly aligned with the other pieces of the speaker driver (it would fall). The surround is an integral piece of the speaker driver that is necessary to generate sound in a dynamic speaker driver.