Magma Single Horizontal Round Rail Mount for Rectangular Grills – T-380. T10-380. Miscellaneous Accessories. The Magma single horizontal round rail mount is constructed from 356 hard anodized aluminum and 304, 18-8 mirror-polished stainless steel with marine grade qualities that add superior corrosion resistance and is less prone to rust. The two-way adjustment system is ideal for horizontal leveling. Easily mount your rectangular Magma grill with no tools, so you can grill out on the open seas. Ideal for sail and power boats, this is a standard duty mount designed for use while anchored or moored and should be stowed while underway.