Hoʻokaʻawale ʻo SO6621-3 i nā mea kani piston i ʻeono pūʻulu: hao hina hina, hao ʻeleʻele i mālama ʻia me ka wela, hao carbide, hao malleable, hao ductile, a me ke kila. I ka makahiki 2012, ua hoʻomohala ʻo Federal-Mogul i ka ʻehiku o nā pūʻulu piston ring, GOE70. Hoʻohana ka mea i kahi ʻano martensite matrix a me ka chromium carbide i hoʻopili ʻia, ʻaʻole kū i ka piko.

ʻO nā mea a me nā helu serial i hoʻohana mau ʻia i kā mākou hui:
Helu waiwai: H9 (GOE13)
Helu waiwai: H6 (GOE32 F14)
Helu waiwai: H11 (GOE52 KV1)
Helu waiwai: H11A (PVD piston ring base material)
Helu waiwai: H12 (GOE56 KV4)
Helu waiwai: H17 (GOE65C SMX70 ASL813)
Helu waiwai: H18 (GOE66 SMX90 ASL817)