The Bio-Rad Helios Gene Gun System is a portable, handheld biolistic device designed for efficient and direct gene delivery into a wide variety of target cells, both in vivo and in vitro. This system facilitates particle bombardment, a method of introducing nucleic acids (DNA, RNA) or other biomaterials into cells by accelerating microscopic particles coated with the desired material. Operationally, the Helios Gene Gun utilizes an adjustable low-pressure helium pulse, ranging from 100 to 600 psi, to propel gold microcarriers (typically 0.6, 1.0, or 1.6 µm in diameter) coated with the genetic material. The system is powered by a 9V alkaline battery, capable of delivering up to 1,000 discharges in continuous use, and features a maximum current of 10 mA peak. The target area for bombardment is approximately 2 cm². Key advantages of this system include its user-friendliness, versatility, and ability to achieve both transient and stable gene expression. It is highly efficient, requiring only small quantities of DNA and cells, and supports the co-delivery of multiple plasmids. Furthermore, it allows for the transfer of large DNA fragments without the need for carrier DNA or the introduction of extraneous genes or proteins. Applications for the Helios Gene Gun System are diverse, spanning gene transfer in plants (both field and greenhouse settings), yeast, bacteria, and other microbes. Accessories such as the tubing prep station for preparing microcarrier-coated tubing and GeneShot control cartridges (pre-made projectiles with reporter genes) are available to optimize its performance and facilitate various experimental setups.