I searched high and low for a forward-compatible front hub, something that would fit MTB boost (15x110) and the currently much more rare Road boost (12x110). It can be done with a DT Swiss hub, but... it's tricky, involving Euro suppliers, etc. Much easier was to support the I9 guys in North Carolina and buy one of their 110 MTB boost front hubs. Then I ordered these 110 'road' end caps... and they fit perfectly. So now, I can use my new front wheel for XC races on my boost MTB fork, or for gravel tours on my MRP road boost gravel fork. Sweet! And of course WBW did a fine job shipping these things to me in a timely way.