A wireless communications system is disclosed. In preferred embodiments, the length-adjustable end caps include a stationary ring member which unitarily includes an annular lip seal, and a connection member in moveable sealing contact with said lip seal. A first plurality of electrical connections is spaced apart by a first distance on the outer region of the substrate. The spring and post members are thereby flexibly coupled such that the upper and lower plates may rotate relative to one another. A difference between TS1 and TS2 defines an underflow recovery period in which data is not read out of the buffer. The requested inactive key to restore is indicated as active in the keystore, wherein the restored key and any other active key in the keystore associated with the at least one storage device with which the restored key is associated are available to be provided to use to encrypt and decrypt data with respect to the at least one storage device with which they are associated.