while i dont know for sure, my guess is that the spk boot is going to fit like a bucket, similar to the 1080 boot. if the 1080 boot fits your foot, then chances are, they krypton wont. its a much much narrower boot with a super snug heel pocket. if you are getting shin bang, either your cuff is not snug enough or you are casing landings or landing backseat. the cuff on the 1080 boot has a relatively snug cuff, but if its still not tight enough for you and you have chicken legs like me, then go to your craft store, get some funfoam stuff and cut it into half inch by 3 inch strips, and glue it to the front of the tongue on either side. that will snug up the tongue around your shin so there isnt so much space. also, put the power strap inside the front of the shell, right up against the liner. hopefully that helps you out.