Stack Flex type 1
Stack Flex gives you the possibility of 'stacking' two outlets on top of each other. By a series connection of the power supply's two outlets you'll end up with a higher voltage on the plug for your pedal. In the case of type 1 Stack Flex it's a black 5.5/2.1mm centre negative DC-plug. One of the power supply's two outlets used with the Stack Flex must be isolated
BE CAREFUL when using Stack Flex. There is a risk of damaging one of your 9V pedals by powering it with too high a voltage. Check the specifications of the pedal and if you still have some questions, you're welcome to send an e-mail to firstname.lastname@example.org and get some useful information.