These shorts are part of the RW-4 race underwear range from Sparco which has been designed with a more relaxed shape. Constructed using a soft touch, flame retardant material for a more regular, comfortable fit with high levels of heat and flame protection.
Highly comfortable soft touch material
Relaxed shape for a more regular fit High levels of heat and flame protection
Sizes

S - 31" to 33" waist (78-85cm)
M - 34" to 36" waist (86-93cm)
L - 37" to 40" waist (94-101cm)
XL - 40" to 43" waist (102-109cm)
XXL - 43" to 46" waist (110-117cm)
Not FIA Approved