Getting a little off-topic, but another option for a reusable link for Campy 5.9mm 10-speed UN chains is the special KMC 10CR link designed specifically for Campy.

https://kmcchain.us/connector/ml-10cr/

I ordered from these guys:

TWO PACK OF KMC 10CR BICYCLE CHAIN CONNECTOR MISSING LINK CAMPY CAMPAGNOLO | eBay

Campy shipped my chain with the guide pin link and I don't have the Campy chain tool you're supposed to use. Park says you can use their chain tools if you hold the chain down in the tool to keep the driving pin centered as you drive the pins. But I always try and have a removable link in my bikes these days so I can give the chain a thorough cleaning off the bike now and then.

Folks seem to have wildly different experiences using other 10s connector links such as SRAM's - some work fine, others have problems. I just decided I didn't want to take any risks so went with the special KMC Campy option and folks seem to have good luck with the Connex one too. YMMV.

- Mark