Hudson Hi-Fi is committed to delivering quality, precision made, high fidelity audio accessories and unique vinyl display solutions at affordable prices. Our sole purpose is to elevate your listening experience. Our products are created and proudly enjoyed by a passionate team of designers, engineers, producers, musicians and Hi-Fi enthusiasts in New York City for music aficionados worldwide. Hudson Hi-Fi Double Sided Turntable LP Alignment Protractor Mat and Stroboscope Cartridge Alignment Tool. The alignment tool provides a diagram for easy cartridge alignment. The flip side, Stroboscope, tests turntable platter speed: Works on 50 Hz and 60 Hz. Tests 33-1/3 rpm, 45 rpm, and 78 rpm speeds. Manufactured from a rigid and durable 3mm acrylic.