VEVOR Linear Guide Rail Set, SBR16 1500mm, 2 PCS 59 in/1500 mm SBR16 Guide Rails and 4 PCS SBR16UU Slide Blocks, Linear Rails and Bearings Kit for Automated Machines DIY Project CNC Router Machines

I would suppose you could use them outdoors, at least for a while. The mounting brackets on the rails are aluminum but the rails them selves appear to be chromed steel. The bearing bodies are aluminum and have plastic parts to retain the ball bearings that are inside. Personally, I wouldn't leave them out in the weather.

Yes, mine are outside. They are coated to avoid rust.

I don’t really know. The rail base is aluminum and the rail looks to be stainless steel but may just be a chrome plated steel. You may be applying some sort of rust inhibitor on a regular basis.

Probably not, it is carbon steel and therefore could rust. I use my indoors (garage) where it is not exposed to the weather. I have no experience with it outdoors.

I'm Sure They Will Rust Not Recommended

I wouldn't they're steel.

Not sure but you could probably drill new holes.

Mine do not, but the aluminum material of the slide block and rail mount makes it fairly easy to fabricate an adapter or other solution...

The pillow blocks align with each other if you were to stack one on the other. May I ask how or what you are building. Just out of curiosity?

Yes, the holes are the same distance apart.

They are an 1" 3/8"

1.150" from center to center. 5.815" center to center lengthwise.