100 % Carbon Construction Weight tolerance +\- 1 grain Components sold separately Inside diameter: .166" Parallel design Weight: 340 spine 8.8 gpi | 400 spine 7.9 gpi |450 spine 7.4 gpi | 500 spine 6.9 gpi | 550 spine 6.5 gpi | 600 spine 6.5 gpi | 660 spine 6.2 gpi | 730 spine 5.7 gpi | 810 spine 5.5 gpi | 900 spine 5.2 gpi | 1000 spine 4.9 gpi | 1150 spine 4.9 gpi | 1400 spine 4.2 gpi | 1600 spine 3.8 gpi | 1800 spine 3.6 gpi | 2000 spine 3.4 gpi