Thanks guys

Mike

groups.msn.com/TheMarylandAR15ShootersSite/whatisana1a2a3ora4.msnw

A1-Rear sight enclosed in carry handle, triangle handguards
A2-Rear sight separate piece of carry handle, round handguards
A3-Removeable carry handle w/A2 style rear sight on the handle
A4-Flat top, no carry handle

a2


a3/a4 (no difference for us lowely civies)


oh yeah, im a visual learner.  

in AR terms-
A1-first style sights no elevation adjustment just 2 aperatures
A2-new style sights with elevation adjustment and 2 aperatures
A3-flat top upper
A4- same as A3

in military terms
A1-rifles you see in vietnam fireing capabilites of Safe,semi, and full auto
A2- new sight system and firing capabilites of safe, semi, and 3rnd burst
A3-same sight as A2 but with firing capabilites of Safe, semi, and full auto
A4-flat top upper with firing capabilities of safe, semi, and 3rnd burst (also ussually has a rail system handguard like the marines m16A4's im sure everyone has seen)