These are used to close off unused fitting connections on components such as Distro Plates and reservoirs. Material: Electroplated Brass. Thread: G 1/4in. Bykski logo: Embossed Included Parts: 1x Bykski G 1/4in. Knurled Plug, 1x Sealing O-ring. Over-tightening is unnecessary and will result in difficult removal. Due to the internal finish, this part may not be compatible with DI water-based coolants and is NOT compatible with PrimoChill Opaque and VUE Coolant Series! Not responsible for any damage caused by or when using this product. Use at your own risk.