These are the two elbow required to mount our Shaker Air Box kit to your stock LS1 motor... You will receive the two BLACK elbows in either 4" to 3.5" (for those with stock size MAF) or, IF YOU REQUEST IT IN THE NOTE AT CHECK OUT (otherwise you get stock sizing) 4" to 4" (for those with 100mm MAF) AND four clamps (not pictured). Shipping within the 48 states is FREE so order today!