Antennas from China isn’t really good choice.
Use google translate and then you can read this https://blog.nic.cz/2013/10/29/projekt-turris-pomozte-nam-vybrat-anteny/ , where CZ.NIC mention it and also don’t forget read comments. 
When you bought router, which cost almost 300$ will you really buy things from China? It could be too danger and also it could be also made in low quality!
Don’t forget this.
As I mention this on IRC (#Turris) anntenas for 2.4 GHz are cheap even in your local shop (TP-Link cost around 3-4€ / per antenna), but antennas for 5 GHz can be really expensive.
Not sure about pigtails quality from China if there can be some problem, but you never know. You should be careful anyway.
I use ebay/aliexpress too for things, where I don’t expect higher quality. They have amazing price for all phone accesories and so on.