Nordicstick
It looks good and is is officially "Don Endorsed".
It appears to be an easy way to perform Nordic Curls.
With that said, Nordic Curls are more of an Eccentric Movement and generally the Concentric Contraction isn't performed due to how hard they are. If it is performed, it is usually with some type of assistance.
Another exercise that would allow a Eccentic-Concentric for Hamstrings with the Nordic Stick would be a...
Glute Ham Razor Curl
The Razor Curl is ofen performed on a Glute Ham Bench; an exercise that primarily works the Hamstrings.
The Razor Curl is still a movement that requires some Hamstring Strength to perform. However, for most individuals, performing the Concentric Contraction in it is doable.
The Nordic Stick would allow individuals to perform a...
Hamstring Floor Razor Curl With Ab Wheel
Evidently, Razor Curls on the floor aren't popular, So, this was the best video demonstration that I could find.
The key, as with the Nordic Stick, is to anchor he heels of the feet.
Having someone behind you anchoring your heels down by pushing on them is one way.
What I do is hook a Car Tow Strap around a Rack or Post so that it anchors my heels in place.
Floor Razor Curl Recommendations
1) Neck Packing
During Razor Curl, tucking the chin down into the chest (Neck Packing) place more of the workload on the Hamstrings and minimizes the back involvement.
2) Banded Razor Curls
a) Reverse Band Loading
For indivudual who need assistance in the Razor Curl Movement; anchor Bands to a Rack or Post behind you and then loop them around the Ab Wheel. This Band Set Up decreases the loading once you are fully extened (your weak point).
It assist you in pulling the Ab Wheel back
The video below demonstrates Reverse Band Loading as a means assistancing in performing Ab Wheel Training,
Ab Wheel Hack - Use Bands to Help
This methiod is employed with Razor Curl, as well.
b) Ascending Strength Band Loading
The use of Band Loading for Ascending Strength Curve Exerises (Squats, Pressing, Deadlifts, etc) ensure Reisistance is maintained through a larger range of the Movement. anchoring the the Band to a Rack or Post in front of you increase as you perform a Floor Razor Curls Contraction,
Ab Rollouts... But Harder
This Ab Wheel video demonstrates the loading effect that is also achieved with Floor Razor Curl Contractions.
Hamstrings
The Hamstrings are Fast Twitch Muscle Fiber.
"Hamstrings should be trained with heavy weights and low reps because they’re 70% fast twitch, ..."
How your different muscle fibre types affect muscle development
medium.com
-types-affect-muscle-growth-1f497dac8674#:~:text=For%20example%2C%20hamstrings%20should%20be,they're%20mostly%20slow%20twitch.
blog.gymstreak.com
