I recently purchased the 8PCS Tatoko D Battery Holder for use in my physics classroom, and I have been blown away by its quality and versatility. The sturdy plastic casing holds the batteries securely in place, and the metal contacts ensure a strong, reliable connection. The holders can be easily connected in series or parallel circuits, making it simple to teach electricity principles to students of all levels. What I love most about these battery holders is their durability. They have held up to high school students' constant use and abuse, and I have no doubt they will last for many years to come. Plus, with the pack of 8 holders, I am able to conduct multiple experiments simultaneously without worrying about running out of equipment. Overall, I would highly recommend the Tatoko D Battery Holder to any science teacher or experimenter looking for a reliable and versatile tool. It has earned a well-deserved 5 out of 5 stars from me!