These rings go with the 37 D.F.A.T Gen 2 HD, or the 55 D.F.A.T Gen 2 HD.
You do need to have the actual D.F.A.T. item linked here to be able to use these scope rings with it. This item listing is for a customer who already has a DFAT and needs to order another ring adapter to be able to use the D.F.A.T. on another scope, or potentially another ring as well as the adapter ring size pending what scope(s) you have and what D.F.A.T. you're using.
any "to 55mm" D.F.A.T. ring will fit the 55 D.F.A.T
any "to 37mm" D.F.A.T ring will fit the 37 D.F.A.T
and any "to 55mm" D.F.A.T. ring will fit the 37 D.F.A.T. with the addition of the "55mm to 37mm" adapter ring in addition to the ring size you need or your scope.
For example, if you have a 37 D.F.A.T that you usually use on your Leupold Mark 4 LR/T 3.5-10x40 with a VX-40mm to 37mm DFAT Ring, and you want to also be able to use your 37 D.F.A.T. on your Mark 5HD 7-35x56 you'd need to purchase the ring for that scope (the VX-56mm to 55mm ring), as well as the 55mm to 37mm adapter ring to make the VX-56 ring be able to adapt to the 37 D.F.A.T.
*IF YOU NEED ANY ASSISTANCE WHEN PURCHASING ADDITIONAL SCOPE RINGS HERE PLEASE REACH OUT via the office line below, WE'RE HAPPY TO HELP!*