For ultimate flexibility you cannot improve upon IAE's range of portable cattle handling equipment - suitable for field usage (can also be used in yard but may require some permanent fixtures).
Standard hurdles are 6 rail z 1525 high with solid bar vertical infillers between the rails for added strength, whilst gates in hurdles and frames can be hung either left or right.
All items are quick & easy to assemble and because of its modular nature you can make the system as large or small as your needs or space will allow.
N.B. IAE also manufacture 7 rail x 1830 high hurdles for use in collecting pens.