SUSTAPEI (Ultem 1000) is an amorphous polyetherimide and is one of the most commonly used high performance materials. It offers excellent thermal performance and high mechanical strength and stiffness. It is inherently flame retardant, possesses good resistance to acids and is capable of operating continuously in steam ® and hot water. SUSTAPEI is offered in Natural (amber transparent) and Black. SUSTAPEI GF 30 (Ultem 2300) is 30% glass reinforced and provides enhanced stiffness, strength and dimensional stability for more demanding applications.