You can post links, but you have to be careful of links that come from blogs or youtube channels, as they are referral links that earn those people money if you click them. Those links, and short links (like a.co links), are auto deleted from reddit as potential spam.

You just have to trim everything off of the end of the link after the product ID before posting it and it will be fine (basically anything after the last section in the following link).

https://www.amazon.com/dp/B00OJM6H7A/

https://www.amazon.com/dp/B00OJM6H7A/

That one should slide down into most vents and stay put (it has two metal pieces that grip into the pipe).