The K2 Darko SPDL is the newest variation of the Darko Series. The difference between this boot and the Darko is the outer lacing type. There is a single track speed lace on the outside and a single track boa for the liner. The heel hold is exceptional but upper and lower adjustability is non existent. If upper/lower adjustability is important to you will want the Darko with traditional lace on the outside and BOA on the inside. At least there you can tie special knots to almost completely separate how upper and lower is tightened. If you don’t care about upper/lower adjustability then you will find the Darko SPDL a very comfortable and responsive binding. It’s also very quick to lace up.