With the addition of the RK300 Rail Mount Kit, you can locate a GM300 or GM500 Mount on stern rails, bow rails, or even downrigger booms. The mounting kit comes complete with a backing plate and two shim sets and allows you to install versatile Burnewiin Mounts on 7/8, 1, or 1-1/4 rails and is ideal for boats like the Boston Whaler Montauk, Axopar, Jenneau and Nimbus.Enjoy the versatility provided by the many options our universal mounts give you. One universal mount, many options: Rod Holders, Fender Cleats, Knives, Downriggers, Flag Holders, or whatever else you can imagine (no hardware included in this kit, all hardware included with mount).WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov