This listing is for a straight 3" x 3" Aluminum Square Cross Member frame piece. These components connect both sides of your trailer frame, keeping them squared and stable. Having a proper working and structurally sound cross member prevents major issues and damage to your boat and trailer. This Cross Member is the 72 inch length. which measures 71 1/2 inches tip to tip, which is commonly used on the main frame of the trailer and also up towards the tongue of the trailer. This is a bolt on style cross member. These most commonly mount to a trailers I Beam Frame using 1/2" x 3" x 4 5/16" U Bolts on each end. Cross Members also double as supports for your trailers Bunk Brackets. The 3" width is the industry standard for most styles of bunk brackets. The straight style of Cross Beam is designed for trailers whose boat does not have a deeper V Hull. You would need to check when switching from a V Bend to a straight to make sure that this adjustment does not effect the loading and unloading of your boat. Using aluminum boat trailer components permanent prevents rust from eating away at your trailer frame, and when using Stainless Steel U Bolts, you will have the best combination to ensure the long life of your boat trailer.