From their site:
I-beam
* All motor application
* 488 grams
* Pro I-Beam design
* Reinforced large end and center section
* Forged in two pieces
* 4340 aircraft quality steel
* Shot-peened
* Silicon bronze bushings
* ARP 3/8 inch 2000 series rod bolts
H-beam
# High boost application
# 502 grams
# Reinforced pro H-beam design
# EDM hole through rod for forced wrist pin oiling
# Forged in two pieces
# 4340 aircraft quality steel
# Shot-peened
# Silicon bronze bushings
# ARP 3/8 inch 2000 series rod bolts
I-beam

* All motor application
* 488 grams
* Pro I-Beam design
* Reinforced large end and center section
* Forged in two pieces
* 4340 aircraft quality steel
* Shot-peened
* Silicon bronze bushings
* ARP 3/8 inch 2000 series rod bolts
H-beam

# High boost application
# 502 grams
# Reinforced pro H-beam design
# EDM hole through rod for forced wrist pin oiling
# Forged in two pieces
# 4340 aircraft quality steel
# Shot-peened
# Silicon bronze bushings
# ARP 3/8 inch 2000 series rod bolts