These are decent highlighters, but I strongly recommend not using them on a premium Bible (like an Allan, Schuyler, etc.), an heirloom Bible, or any other Bible that you want to keep in tip-top condition. However, they are great for "knock around" Bibles, study Bibles, or Bibles you want to use for entry level or intermediate art journaling. While these highlighters could be a good choice for journaling and whatnot, be warned: once you highlight a passage it may be hard to mark over it with a pen, so please consider marking/drawing with a pen before you highlight. That is the biggest drawback to these highlighters and why I removed one star and referred to them as "decent." The pen used to test was a Sakura Pigma Micron 01. These pens are very Bible friendly, and are smear proof virtually the instant you put the ink on the page. However, when marking over a highlighted passage, due to the highlighters waxiness, the pen's ink will smear even after allowing ample drying time. That is a real drawback because one may be inclined to go back some time after they have highlighted a passage and mark it with a pen, but, at least with the Microns, it probably won't turn out so pretty. I did not test the integrity of the highlighting when subject to high heat (say leaving the Bible in a hot car during the summer for an extended time), but I would not be surprised if doing so led to increased stickiness of the highlighted passages or something similar. Also, this product quickly loses its tip and becomes blunt which makes precise marking a challenge. While the highlighters are very waxy, the colors are very vibrant and quite pretty. The highlighters made the pages stick to the point where thumbing through the Bible's marked pages became a challenge and the color did transfer to the opposite facing page but the color transfer was not too bad and much of it can be wiped off with a dry cloth or even better, a good-quality pencil eraser. To note, I learned a little trick: after you highlight and give the marking ample time to dry (an hour or so) you can take a piece of cloth, put it over your finger and rub/buff the highlighted section and it and it will reduce stickiness but also it will reduce the vibrancy of the colors as well. On the upside, I tested these highlighters on a Bible with relatively thin pages and there was absolutely no bleed through. All that said, I like these highlighters and would buy them again but, again, only for my knock around Bibles. I WOULD NOT mark my higher-end or "special" Bibles with this product. I am using it on a Bible from "Church Bible Publishers " that I intend to heavily highlight and mark up and take with me when I travel. For that, the highlighters will be great, but I want the reader to be careful purchasing these and using them in one of those Bibles you may have that you want to be very careful to keep in excellent condition. If you want to highlight higher-end Bibles or don't feel like dealing with gel highlighters, consider using a nice, smudge-proof color pencil. Color pencils are a rabbit hole that is deeper than this review is intended to go, but there are some suitable ones out there. I have included a picture with this review to give you more insight into this product. I really hope it helps you in making a decision. Enjoy! EDIT: For the sake of openness, this review has been edited by its author. I had originally gave the product 4 stars but after using it extensively I removed one star. Furthermore, I tweaked some of the writing, and also edited the included picture to make my notes more readable. My sincere apologies to the community for rushing into a review, it will not happen again.