I recently stumbled upon these rectangular tubing inserts in the Biscuits & Plugs category of Industrial and Scientific hardware and they have become the perfect solution for my industrial needs .As my tests showed they provide excellent durability and resistance against extreme temperatures, making them an ideal choice for any application. Furthermore, their lightweight design makes them very functional and easy to install. However, their availability in only a few standard sizes is a bit of a drawback. Despite this, I highly recommend the pieces as an exceptional tubing insert solution..