Sound prints in Super 8 were plentiful and considering that they were very expensive by modern-day standards, sold in appreciable quantities. A two-reel print (running approximately 17 minutes) cost around $50, with feature films costing at least $150-plus. A few prints were also released with stereo sound. In Europe, optical prints were also popular and were appreciated for their often superior sound quality. In theory, magnetic prints should have been superior, but Super 8 magnetic prints were often poorly recorded after the picture was processed, due to high-speed, mass production techniques. An optical track, on the other hand, could be printed at the same time as the image and in equivalent quality.