The flexible PCB battery interrupters work very well overall. They’re notably thinner and tougher than the ones often made by hand from copper tape. Also, they have cutting outlines, so you can trim them to fit the type of battery cell you’re using. This means they’re far less likely to fail, by sliding out of position. There are some caveats though, that all battery interruptors have, including our MMC ones. First, the switch and cable you use, must able to handle the full rated current drawn by the device. This is important to know, because some assistive switches were intended more for signalling PC’s than for powering devices. A switch unable to handle the required current could overheat and burn out. Also, due to the thinner construction, battery interrupters are likely be more fragile than regular wires, so they should be covered, reinforced, and protected where possible. Finally, the longer wires and cables in a battery interrupter can potentially introduce electrical noise, which could adversely affect some sensitive circuits, such as radio and wireless systems. Check for proper operation (not just power up) in these systems if you add an interrupter.