Those glasses are made out of Shape Memory Alloys (SMA), from which the most common ones include nickel, titanium, copper, zinc, or iron in their composition. I don't think the tag: grade of titanium, is applicable for SMAs even it they contain a high percentage of titanium.
As a functional materials, their properties and applications are so different that they have their own system. For example, one of the most recognizable brands of SMAs, Nitinol (nickel-titanium):
...offers different grades of Nitinol, which are distinguished by the
austenite start temperature of the ingot:
Nitinol #1 (superelastic) -35 to -10 °C
Nitinol #2 (superelastic) -45 to -15 °C
Nitinol #4 (superelastic) -10 to +10 °C
Nitinol #5 (shape memory) ≥ +85 °C
Nitinol #6 (shape memory) +35 to +85 °C
Nitinol #8 (shape memory) +10 to + 35 °C
Nitinol #9 (superelastic) ≥ +35 °C
It is possible to tune the shape-memory and superelasticity properties of the alloy by modifying its composition. And speaking about the glasses (spectacles), you are more interested in the superelasticity behavior of the material rather than in its shape memory effect.