Been shooting GT 33/55 and 55/75`s for last few yearss and want to try something different..what other manuf. arrows are the same or close to equiv. spine..also can someone please explain spine designations like 2000,3000, 4000 or 340 400 etc. Only other carbons Ive shot alot were ACC 3-60`S in my compound days and the Blackhawk equiv. Thanks, Dean

GT 35/55 has a spine around .480 for those an Axis/Beman MFX 500 or Beman ICS 500 would be close.For the GT 55/75 has a spine closer to .400 would be Blackhawk 3000(.400) and Axis/MFX 400 or Beman ICS 400 are some suggestions.