These were mine originally and compensated for the wrong offset wheels I used to have. They originally cost me around £115 from SRB, I was told that the bolts were toughened steel and after pushing the old ones out, put these through with some difficulty as I recall having to move the calliper out of the way. Once the wheel went on and the nuts were torqued up to standard they remained in situ through around 5000 miles, or however long it took me to wear the new tyres out, then I swapped the wheels so sold them on.
H&R hubcentric are up there with the best money can buy in spacers world, my father in law (engineer) helped me put them on and he was impressed with the quality, especialy after seeing many halfrauds type spacers in the past. Having lost a wheel around 30 yrs ago, (had a couple of extended wheel studs sheer off on a cheap set), I was not going to fall for that again, which was why I was pleased that these came with the extended bolts rather than another add on. Also bear in mind they make them well past 25mm so these are not the longest bolts they make...
Once on they never caused any issues except for the slightest arch rub.
Just get them on and enjoy your new wheels matey