They are closer to Easton Injexion arrows,close to the same diameter.They are a G-nock size in diameter.Easton uses their new Deep Six HIT inserts with 6/40 thread size.The VAP have a couple of different insert sizes.They fit down inside the shaft and are like an outsert,one size flares up to a 9/32" point or a 5/16" point.And the inserts,one is aluminum at about 43 grs. and a stainless steel one at about 110 grs..You said the 200 spine has about the same GPI as your Axis Traditional 400,but a 200 spine is alot stiffer then your 400 Axis.