Kettler skylon 5 cross trainer the kettler skylon 5 cross trainer is a top of the range machine brimming with features including a high tech computer and memory for 4 users let the whole house record their sessions to track their fitness the heart rate light on the console ensures you maintain a healthy work balance the back lit console turns green or red depending on whether you are working safely or your heart rate is too high the zero impact design of the cross trainer protects