Fantastic option for mounting batteries especially if your water bottle bosses aren't ideally positioned for your downtube battery (ie Built-In Controller Batteries).

Also features hose clamp attachment points to allow a battery to mount without water bottle bosses at all!

The design incorporates a hollowed out center allowing the mount to "cup" around the tube and make 2 connection points, making a very sturdy mount.

From Grin's website:
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The Triple Bob rail provides for a convenient and secure means of attaching a Hailong-1, 21700, and Reention case Downtube battery to any any location on the bicycle frame tubing
regardless of the eyelet position. These pieces are CNC machined from solid aluminum stock and provide a wide and flat platform for the battery cradle to rest, secured with three M5 bolts so there is none of the rocking or play that is sometimes present with waterbottle eyelets. Machined channels allow up to 4 hose clamps to keep the battery tightly in place, and comes with heat shrink for hose clamps. Designed and made in Canada by Grin Tech.