Yes they are red.

Yes, red leds

Yes, red

yes they are red.

The LEDs on the Knog Gekko LED Rear Light are definitely RED!
I have one of these lights in front of me now!

Yes LEDs are red

Yes, very bright red

Always click on rear lights as these will show you all lights in red.

Yes, they are red.

They have clear lenses but they do produce a very nice red light.

Yes

Yep, but you're better off mounting them on your stays. You'll see what I mean if you get them. They are great : )

Yes, the stretchy fixing system will fit all seatpost sizes

the fastner is rubber so should fit a variety

I think it would because the casing is flexible and stretchy (to a degree)

nice and stretchy, it will fit any seatpost.

it should

Yes will fit all seatpost dimensions

Yes. The silicone would have enough stretch to fit that diameter post.

Yes as it fits suspension forks, make sure the legs are not twisted as it will strain them more.

It is pretty flexible for mounting, but really is designed for the seat post. If you dont mind fiddling around im sure you could get it to mount on the stays.

Seat post best, may have to use packing ie. a bit of garden hose on seat stays.

would think so might need a small bit of packing but with it being make of rubber should hold quite firm

It will fit on the seat stays but may be a little loose and swing around over bumps. I would recommend choosing a tighter fitting light for stays. It will also likely point the beam up into the eyes of other road users if mounted on the stays as there is no means to angle it away from the angle of what it is fixed to.

works on seat stays fine on my giant boulder.

Not really, mate.

No it needs to fix onto the seat post

That is a no-go. The built-in rubber-band attachment method will work with a limited range of seat-post diameters.

I'd probably look elsewhere. Depending on the thickness of your stays it might stay on, but it's fairly thick and might come into contact with your spokes. Definitely designed around fitting to a seat post

Try Topeak as they come with a choice of brackets.

Needs to fit on a round (not aero) seat post ideally.
Seat stays would be too thin and led's are angled slightly for a seatpost, so would not be at the correct angle even if you did attach to seat stays.

No, this is not really adjustable fit.

Designed for a standard seatpost.

as its rubbery it tends to stick!
but the fitting cannot be made tighter, it wont be a snug fit. if it rotates watch spokes!

Might be a bit loose, but can use packing and should be ok. Great lights

Should do, might be a funny angle

I doubt it, unless you wrapped some tape or similar around your rear forks to make them fatter. It's designed for seatposts.

Yes. Easy

I mounted them on my seat stays. They are too big for a typical seat post if you have a bag as well.

No, it will be far too loose.

I do not think it would fit an aero seat post.
It needs to fit against a round section ideally, and the strap would not really stretch that much.

I got one around my bike's seat tube so... about 12cm maximum circumference but the light mechanism's hard plastic body is quite curved so if your seatpost's trailing edge is a bit sharp then it won't fit.

It's really meant for round-ish tubes - non-aero seat posts, seat stays.