From New Telemark Guide
NTN Boots
See NTN Boots for more details.
What boots will work with NTN?
Only specific NTN boots are compatible with NTN bindings. The difference is that NTN boots feature a second heel underneath the boot which NTN bindings clamp onto. Sometimes this is referred to as a "duckbutt". Beside the differences in the duckbill, 75mm boots lack this second heel.
What boot sizes are available with NTN?
As for 09/10, Rottefella's NTN binding specifies 32.0 mondo and smaller. NTN bindings break down to two sizes: Small (for boots 26.0 mondo and smaller) and Large (boots 26.5 to 32.0). Boot manufacturers however may not provide all possible sizes. Currently, we've only seen them offer boots 24.5 - 30.5.
Can I use different NTN boots with the same NTN binding?
Yes. NTN is designed so that you can swap boots easily, especially if the boots are of the same size. So long as you don't put a small boots into a large binding (and vice versa), swapping will not require any sort of binding adjustments.
Can I use NTN boots in 75mm bindings?
In most cases, no. Most 75mm boots use a set of wings to match the duckbill. NTN boots lack this duckbill. Some exceptions may be with Bomber Bishop bindings, as they use an adjustable rod for toe hold-down.
Can I use NTN Boots in traditional DIN alpine bindings?
In general, this is not recommended. DIN bindings use a hard plastic boot sole to help the boot release. NTN boots have rubber vibram soles which may interfere with the release mechanism. If you decide to do it anyway, stiffer boots, like the Crispi Evo, seem to work better with DIN bindings. Softer boots can cause the ski to pre-release.
Which NTN boots are Dynafit compatible?
Scarpa Terminator X or Terminator X-Pros boots work with Dynafit bindings. Crispi is slated to offer their two NTN boots with Dynafit compatibility for 2011/2012 (Evo Freeride and Shiver Freeride).
Do NTN boots work in Bomber Bishop bindings?
Yes they do work. Do they work well? No.
The current revision of the Bomber Bishop is designed for use with 75mm telemark boots, and relies heavily on the lever action of the duckbill to prevent the boot from pivoting up onto the toe. While a NTN boot will fit into a Bishop, the result is an extremely neutral performance. Read more about it from TelemarkPhat.org
What boots should I get?
The bindings currently don't have make by way of setting activity level through changing or adjusting powertubes. It's better to choose your activity level by selecting at boot that matches the flex you desire.
Which boots are soft/stiff?
See Boot Flex Scale.