The Rock River Arms CAR A4 - 16 Inch - CHROME LINED - R4 Lightweight - Basic Upper features a Rock River Arms 16 inch CMV, chrome lined, R4-lightweight profile barrel, chambered in 5.56 NATO with a 1:9 twist, carbine length gas system, front sight tower with bayonet lug, and a 1/2-28 threaded muzzle.  Built on a Rock River Arms forged A4 flat top receiver with carbine length plastic handguards, sling swivel, and an A2 flash hider.

Complete with RRA AR-15 bolt carrier group and forged charging handle.

The Rock River Arms MID A4 - 16 Inch HBAR - Basic Upper features a Rock River Arms 16 Inch CMV, HBAR profile barrel chambered in 5.56 NATO with a 1:9 twist, mid-length gas system, front sight tower with bayonet lug, and a 1/2-28 threaded muzzle.  Built on a Rock River Arms forged A4 flat top receiver with mid-length plastic handguards, sling swivel, and an A2 flash hider.

Complete with Rock River Arms AR-15 bolt carrier group and forged charging handle.

FACTORY BUILT BY ROCK RIVER ARMS INC.

The Rock River Arms CAR A4 - 16 Inch HBAR - SINGLE RAIL GAS BLOCK Upper features a Rock River Arms 16 inch CMV, HBAR barrel chambered in 5.56 NATO with a 1:9 twist, carbine length gas system and 1/2-28 threaded muzzle.  Built on a Rock River Arms forged A4 flat top upper receiver with standard CAR length plastic handguards, Rock River Arms clamp style single rail gas block, and an A2 flash hider.

Comes complete with Rock River Arms AR-15 bolt carrier group and forged charging handle.

The Rock River Arms 24 inch - Varmint A4 Upper features a Rock River Arms 24 inch stainless steel, air-gauged, cryogenically treated, bull barrel (barrel diameter of 1.050 under handguard, .920 diameter gas block journal) chambered in .223 Wylde, with a 1:12 twist, rifle-length gas system and a target crowned muzzle.  Built on a Rock River Arms flat top receiver with an RRA TRO-STD handguard (14.5 inches long) and a low profile gas block.

Included: 1 bottom rail, 2 2" short rails