The modules arrived fast, and they work after we spoke with support to get the right ones.
So far, we are extremely happy with FS!

Hello, they worked well. We just ordered another 83 of them. Thank you

Thanks for reaching out, FS.com has had excellent service since we opened our account – I plan to continue ordering cables, jumpers and modules when needed.

After sales is second to no-one!
Delivery was timely and also well shepherded.

We explicitly chose FS because we know you are usually able to ship next day, which is highly appreciated.

Everything is great as always from you all! Appreciate it.

Wow, thank you so much!

The modules are working fantastic, as expected.

Thank you for following up. We have received modules. Your website and service is excellent. Thanks.

I am writing to you to confirm that I received the first package (with everything except the NIC).
I can confirm that these 10km transceivers are working well, even with the 20m cables! They are a bit overkill and expensive, but due to the limited boring diameter we can afford, they will be much better for us than duplex transceivers.