TPE (Thermoplastic Polyethylene) It is flexible at room temperature (and low temperature) and is a popular choice for 3d printing. It is sometimes harder than TPU depending on the additives.
Ease of Use
Print in better quality at 223°C nozzle temp with fan on at 40% starting the third layer.
Print at a slow speed.
Cold, sanded acrylic bed recommended. Leave sanding dust on bed for an easier removal.
Keep an eye during the transition between the first layer to second layer, tends to spaghetti out filament out of extruder.
You can tight more the spring arm on extruder to release tension and avoid spaghetti.