Athlon Optics Helos BTR 1-4.5x24mm ATSR3 Rifle Scope 30mm Second Focal Plane IRMOA Reticle Black 214101. 5x24 Second Focal Plane Rifle Scope. To hold up against all odds these AR15 Rifle Scopes by Athlon Optics are waterproof fogproof and shockproof -...