See Brady Products
Crystal 20.0000MHz SERIES SMD - 20MHz - ±50ppm - ±30ppm - Series - 40 Ohm - Fundamental - -10°C ~ 70°C - Surface Mount - 4-SMD - No Lead (DFN - LCC) - 0.236" L x 0.138" W (6.00mm x 3.50mm) - 0.043" (1.10mm)