Wrenn decided, like Scalextric, VIP and SRM, not to invest in supplying a power unit with their Sets. This would have severely added to an increased price for their Sets. However, just like their competition, they ultimately had their own Power Units manufactured later and added to the range. There were ultimately four different types of Power Units made available – the AC version was originally available for the Vibrator-motored cars with either an input voltage for the UK market or a corresponding one for the overseas market Subsequently DC versions for both markets were manufactured which had twin outputs. Each Power Unit was supplied in a special corrugated cardboard box with a White gummed paper label having Blue printing which identified the type and voltage of the Power Unit.