These are nice to have on your bars to keep water and other debris out of your rails. That being said you do not need to buy these if you are buying the railgrabber also because a set of four are included. I learned the hard way. No biggie I just payed like $8 more than I needed to. Just read about the product or ask a rep before purchasing both.
Unless you use some other accessory at the end of the bars you need these. You can live without them, but to have a yakima rack system and unfinished bar ends would be silly. Without these the ends are rough and ugly. And without these you will probably get some stuff and moisture inside the bars. You can live without them if you like but it would be silly.
A maximum of 50,000 bonus promo points can be earned on the 3XREWARD promotion code. Moosejaw Points are cut in half for sale items. So, if you get something on sale you'll actually get 15% back in points instead of 30% back. Promo Points cannot be earned on Gift Cards, Patagonia, Western Mountaineering, Montbell and Marmot. This promotional code can only be used once and is good through May 4, 2014. Your reward points won't show up in your account until after your order is shipped. See site for all program details.