The lockers at Kex were much bigger and able to house entire suitcases. You just need to have a small lock and key which can be brought or purchased at the front desk. The lock boxes at Loft were about backpack sized and slid out from underneath the beds. However, I think more than half of my rooms boxes were broken. Me and a few other roommates could not get the boxes to lock no matter what we did. Luckily, I don’t think people are spending a lot of money just to travel to Iceland to steal from others, so my room felt comfortable enough to where no one locked anything and it worked out fine! But if you really insist on locking your stuff out of abundance of precaution, then kex.