3-1/2", 45 degree sailing clinometer. White numerals are engraved and paint-filled by hand, for maximum durability, readability, and weather resistance. Tube assembly is made of tough, durable borosilicate glass. Housing is made of heat resistant, high-impact ABS polymer. Background of tube assembly is brilliant, fade-resistant "Neon Yellow" for high visibility. Anodized indicator ball. Mounts optionally with high-bond tape adhesive (provided) or with screws (not provided). Tape adheres well to most surfaces.