Yes, OM4 can be downward compatible with the corresponding cable, but the transmission is limited by OM3 cable. By FS.COM on May 28, 2018

They could be used together while the FHX cassette should match for FHX enclosure and the FHD cassette should match for FHD enclosure. They're only different in package style, but the cables sequence and interface of the model are the same. Usually, the FHX series products can be configured in the central apparatus room, and the FHD series products can be configured in the branch room. By FS.COM on May 17, 2018

There is a label beside MTP adapter on rear and the package of every cassette, marking what polarity the casssette belongs to. By FS.COM on December 23, 2017

Certainly, this cassette is designed with plug-style lock, without any tools, you can quickly remove and easily install. It is mated with our FHD series fiber enclosure, like 51607, 34684, 50550 etc. By FS.COM on November 11, 2017

The best solution of carrying up to 6x40gbps connections is Enclosure（eg.#51607）and MTP Adapter Panel（eg.#35506）. If combination of 10/40 gig optic connections, you could deploy Enclosure with MTP Adapter Panel(40G connection) and MTP Cassette(10G connection), 1U/2U/4U enclosures are available, no limit for throughput. By FS.COM on October 21, 2017

Male default. MTP male connector can be connected with MTP female cable. However, if you had MTP male cable and want one cassette with built-in MTP female connector to link, we can also do it. By FS.COM on August 16, 2017

Our MTP-12 cassettes are configured in accordance with the TIA Connectivity. Type A and AF should be used a pair in a two cassette method A link, using type A MTP-12 backbone cable to connect; B1 and B2 should be used a pair in a two cassette method B link, with type B MTP-12 backbone cable to connect. However, there is a limitation of method B that it doesn’t allow use of an angled polished (APC) single-mode connector. By FS.COM on August 16, 2017