The StackMat Pro Timer G5 is the latest iteration of the StackMat Timer. There are quite a few changes from the G4, those include: Two operation modes: 4-Pad (for stacking) and 2-Pad (for speed cubing). Just hold the RESET button for 5 seconds to switch modes. RESET and POWER buttons have a new reinforced design that won’t wear through with extended use. Hold-feature on RESET and POWER buttons prevents lost times when a timer is slammed. TD cord plugs in underneath the timer so it’s out of the way and doesn’t accidently get unplugged. A new snap-in G5 button system eliminates timers getting knocked off the mat inadvertently.