6-4 Titanium direct thread adapter.  This adapter has an internal hex on the backside. Specs are as follows:

It has a (1-3/8 x 24tpi) external thread. 

The external hex accepts a 1" wrench and the internal hex accepts a 3/4" socket. 

Overall Length is 5/8"

Internal threads available are 1/2"x28tpi, 5/8"x24, 1/2"x36tpi and others available as a custom order.

Product weight is 40 grams