Light for aero seatpost

[Ross]

A friend of mine is looking for a stealthyish rear light to clip onto the seatpost of a Pinarello Dogma (they have aero seatpost).
A few criteria:
Preferably clips on with a rubber type band (like Moon and a few other brands), not with a bracket that is screwed to seatpost that light slides into
Preferably has normal AA/AAA battery/s rather than USB rechargeable
Needs to be reasonably bright, not retina burning but PBSF or above brightness. So no $2 Alibaba glow worms
Needs to have reasonable run time, more than a few hours
Would a light that could be attached to seat stay
Must be internal battery/s, not external

[warthog1]

I have one of these;
https://www.serfas.com/products/view/669/
Bright enough but not too bright and runs for a few hours.
usb rechargeable though.

[ldrcycles]

Bunch of candidates in this thread. I needed to search for that anyway, i've been putting one on the seatstay of my new TT bike but it's far from ideal.