@kristof-delaere The terms that you refer to are footprint/package specifications (size, shape). Here are links to the above components on digikey: CMOS SMD (oscillator) http://www.digikey.com/product-detail/en/epson/SG7050CAN-27.000000M-TJGA3/SER3999CT-ND/5175091 0207W (120 ohm resistor) http://www.digikey.com/product-detail/en/tt-electronics-welwyn/WRM0207C-120RFI/985-1466-1-ND/3648019 0207W (2.7k ohm resistor) http://www.digikey.com/product-detail/en/yageo/MCP100JR-2K7/MCP100JR-2K7-ND/2169183