I do not know anything about these other than the fact that they're brand new I don't have the original box I will ship in a generic box. This listing is for one unit please send me a message if you have any questions

Doing some research this is what I found.

The STM-4 (Synchronous Transport Module) is a SDH ITU-T fiber optic network transmission standard. It has a bit rate of 622.080 Mbit/s.

The STM-4 specification is designed to carry 7,680 8-bit "voice" frames every 125 micro-seconds for a total payload bit rate of 491.520 Mbit/s. The other levels defined by the SDH standard are STM-1, STM-16, STM-64 and STM-256. Beyond this we have wavelength-division multiplexing (WDM) commonly used in submarine cabling.

Although STM-4 is comparable to OC-12 the SDH frame structure allocates more space to overhead than that of SONET. Because of this, STM-4's payload bandwidth differs from that of OC-12.

Information in this listing was copy and pasted from the manufacturer site. Please do your own research when cross-referencing any features , specifics and or dimensions as I am not liable for misprinted information. If you have any questions please message me.

I do accept domestic returns, in the timeline listed in this add. If you have any issues please message me first for resolution . The buyer is required to pay return shipping. the item must be returned in the exact condition sent, in the original packaging, untampered with, unopened and unused.

If you are international buyer you will need to purchase the label on your own for return, and anything over 750 signature is required.  Return address is listed in the original label, or if you need confirmation of return address please message me.  I cannot purchase labels out of country due to signature safety of goods disclosure, on cross border returns. Example (Shipper needs to sign disclosure on cross border shipments) 

"International buyers – please note: Import duties, taxes, and charges aren't included in the item price or postage cost. These charges are the buyer's responsibility."

"Please check with your country's customs office to determine what these additional costs will be prior to bidding or buying."