Thats a very smart headcollar and he looks great in it. But I think what Marty means is that normally minis have to wear headcollars that are fully adjustable - nosebands and under neck 'strap' as well as the main head piece. To fit your headcollar correctly you would need to loosen both the noseband and the under neck strap to enable you to lift the whole thing higher up his nose. The noseband should sit just under the end of his cheek bones - any lower than this and it is possible for the naughty 'ones' to rub themselves out of their headcollars, which can actually be quite dangerous for them. Sorry, but you cannot just make more holes in the top head strap as in pulling the headcollar up higher, you will make it too tight under his throat - and of course too tight round his nose. (It is important not to put anything round his nose that might cause his 'cheeks' to rub against his teeth at any time in his life, but particularly during his 'teething' years)
It is such a lovely headcollar so could you perhaps take a few measurements and then take it to a saddler and get them to make some 'additions' to the nose and under his throat to make it a perfect fit for him?
Anna