A very good saddle replacement or an upgrade. The plastic is unique and does produce a good tone, it has a certain hardness that would mean it has a long life and durability. Its easy to sand down to get a perfect fit. These TUSQ saddles do improve the tone compared to a regular plastic saddle, I even prefer it to the sound of a bone saddle.
Its also recommended to have several of these saddles that can be fitted to suit different playing styles, string gauges, and so on. For example, slide guitar with a very high action where no fretting is needed, or a thin gauge of strings for finger picking. Being able to exchange these different saddle setups allows multiple uses for one guitar.