Each die has 6 faces with letters Q, R, S, T, U, and V. The total number of outcomes when throwing two dice is:
\[
6 \times 6 = 36.
\]
Now, we are only interested in the outcomes that result in Q, U, or V on both dice. The favorable outcomes for each die can be one of the three letters: Q, U, or V. Therefore, for both dice:
\[
3 \times 3 = 9 \text{ favorable outcomes.}
\]
So, the probability of getting only Q, U, or V on both dice is:
\[
\frac{9}{36} = \frac{1}{4}.
\]
Thus, the probability is \( \frac{1}{4} \).