The RPM Front A-Arms for the ARRMA Big Rock 4X4, Senton 4X4 & Granite 4X4 (#81492) are a heavy-duty, engineering-grade nylon suspension arm pair designed to replace stock ARRMA front arms (#AR330443). 
They reduce unsprung weight, resist cold-weather snapping, and add an extra outer shock-mounting hole to lower ride height for sharper cornering.
Includes a second shock-mounting hole outboard of the stock position to lay the shocks down slightly, lowering the center of gravity and improving high-speed stability.
Important Big Rock V3 Note: As RPM R/C Products warns, newer Big Rock 4X4 V3 (#ARA4312V3) models switched to wider Typhon 3S suspension arms (#AR330543)—if you have a V3 Big Rock, you need RPM #80762 instead.
Fits standard-width 4X4 3S BLX and MEGA models using #AR330443 front arms, including the Granite 4X4 (#AR102665, #AR102666, #AR102676), Senton 4X4 (#AR102667, #AR102668, #AR102678), and V1/V2 Big Rock 4X4 (#AR102711).