MaxSea TZ Explorer software (not Navigator) has a cross license agreement on MM3 charts with NN3D. If you purchase the software, please contact our tech support with your MaxSea PC software license number and your NN3D System ID number. We can "connect" your two licenses together. This way when you purchase of one Map area you get two unlocks codes (one for the MaxSea PC and one for your NN3D system). The unlock codes are not the same. Both systems are unlocked for the cost of one.