Thank you for your question about the aramid material. PITAKA started as experts in materials science, we fully understand your confusion. 

Aramid （learn more here https://www.ipitaka.com/pages/material ) is the chemical name of Kevlar, while Kevlar is the aramid brand name of DuPont.

1500D and 600D are professional terms for the number of aramid yarns. 

D, shorten for Denier, indicates the linear density of the aramid yarn. 

The 1500D is our classic work, while the 600D is our latest creation.

600D aramid fiber is exquisite and stylish but twill deformation is very likely to happen before its solidifying, so its yield rate is very low and the cost of manufacture is high. PITAKA is one of the few companies that adopt selective 600D aramid fiber in manufacturing products. Compared with other aramid fiber of different deniers, like 1500D aramid fiber, 600D aramid fiber is harder to produce, so its supply is limited.

600D aramid fiber is a new high-tech fiber with great strength and modulus. It’s about 5-6 times stronger than steel wire but its weight is just about 1/5 of the steel wire. In addition, for a small or medium-sized product made from 600D aramid fiber, there are more lattices per unit of the microgroove fiber cloth, which means more mix of twill and plain weave. It makes the product more beautiful and more comfortable to touch. 

In other words, the product of the same model made from 600D aramid fiber is lighter and softer than that from 1500D aramid fiber.

Both of them are elaborately made after a series of complex processes such as rigorous weaving, impregnation, vacuum forming, multi-axis laser cutting, manual polishment, spraying, etc.

At present, the selected 600D materials of aramid fiber are used in the production of AirCase and AirPal mini for AirPods Pro.

Hope this information will help you better.