For use with Easton 4MM arrows shafts Break-off shank will fit arrows with .167" ID Sold in a 12 Pack Including: Easton Super Drive Micro Spine 325 use #4 Easton Super Drive Micro Spine 375 / 425 use #3 Easton Super Drive Micro Spine 475 / 525/ 575 / 625 / 675 / 750 use #2 Easton Super Drive Micro Spine 850 / 950 use #1 A/C/E (all spines use #1 or #2) ProComp (1150-810 use #1 | 710-520 use #2 | 470-380 use #3 | 340-300 use #4) Avance (2000-900 use #1 | 1150-730 use #2 | 730-500 use #3 | 500-340 use #4) Weight: #1 60-80 grains #2 70-90 grains #3 90-110 grains #4 100-120 grains Previous Easton shafts Carbon One ( 2000-900 use #1 | 810-730 use #2 | 660-500 use #3 | 450-410 use #4) A/C/G (1500-710 use #1 | 710-480 use #2 | 480-430 use #3) Apollo (2000-1200 use #1 | 1070-950 use #2 | 840-670 use #3 | 610-560 use #4)