8.3. In the tetrahedron $K L M N$, it is known that $K L = M N = 4$, $K M = L N = 5$, $K N = M L = 6$. Points $P, Q, R, S$ are the centers of the inscribed circles of triangles $K L M, K L N$, $K M N$ and $L M N$. Find the volume of the tetrahedron $P Q R S$. Round the answer to the nearest hundredth if necessary.
Answer: 0.29 (exact value: $\frac{7 \sqrt{6}}{60}$ ).