https://www.samtec.com/jp/standards/jtag

JTAG 20 pin dimensions

ARM Standard JTAG Connector (20-pins, 0.10")

The header (e.g. a Samtec TST-110-01-L-D) is a 20-Pin, 0.10" (2.54 mm) pitch connector with these these dimensions: 1.3" x 0.365" (33 mm x 9.27mm).

https://www.digikey.com/product-detail/en/samtec-inc/TST-110-01-L-D/SAM10837-ND/2685837
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FTSH-110-01-L-DV-K

It's dimensions are: 0.50" x 0.188" (12.70mm x 4.78mm).


https://www.samtec.com/products/ftsh-110-01-l-dv-k

Connectors

http://www.keil.com/support/man/docs/jlink/jLink_connectors.htm