This Grade G10-FR4 fiberglass-epoxy laminate is chosen for its extremely high strength and high dimensional stability over temperature.
These phenolics (garolite is a brand name) are made from glass cloth that has been impregnated with an epoxy resin under pressure and heat.
Use it for the same things you would with carbon fiber, but at a fraction of the cost.
Will not conduct electricity or interfere with radio signals.

2 Sizes: 20.32x25.4cm (8x10") and 40.64x25.4cm (16x10")
3 Thicknesses: 1.59mm, 2.38mm, 3.18mm (1/16", 3/32", 1/8")
6 Colors: Black, blue, green, orange, red, and camouflage!
Garolite Density: 1.83g/cm³ (1.06oz/in³)
Weight (8x10" sheet):
- 1/16": 150g (5.29 oz)
- 3/32": 225g (7.94 oz)
- 1/8": 300g (10.58 oz)
Flexural Strength: 70,000 psi
Tensile Strength: 3160kg_f/cm² (45kpsi)

*Tip: If you need to countersink garolite, or are worried about frayed edges, simply drip or dab some thin CA glue onto the exposed areas.  The garolite will absorb it and become much stronger.