Unless otherwise noted on the listing description, Nagra tape recorders of the “4 series” listed for sale on the Trew Audio consignment pages are fully inspected and serviced at Trew Audio by Glen Trew, calibrated for modern tape, and guaranteed to perform within original Nagra specifications. The “4 series” machines include stereo models IV-S, IV-SJ, IV-STC, IV-S Timecode Systems (“Havey Mod”), and mono models 4.2 and IV-L. Professionals and serious amateurs can be sure that when purchased from Trew Audio these tape machines can be used for reliable high quality recording and playback, as originally intended.