https://www.edmundoptics.com.au/p/hoya-uv34n-340nm-254mm-dia-25mm-thick-colored-glass-longpass-filter/46444/
Hoya UV34N (340nm), 25.4mm Dia., 2.5mm Thick, Colored Glass Longpass Filter
Hoya Colored Glass Longpass Filters used in optics and photonics applications are available at Edmund Optics