This modular system can be expanded. The stems are handy on a keychain or in your pocket as an RDA stand / Tank Stand. They are 7mm unthreaded and will accept the threads of your 510 atomizer for secure storage or building, without damaging them. The tree is useful as a single stackable system or as a flowered display. The print used in the images was a draft print for display purposes. Print as many stems as you need. We use them in our shop to display new items for sale.