I recommend Higher Mark Performance Tack. This company makes biothane tack and has Beta, normal Biothane, tons of colors, and lots of widths. Jean (owns the company/makes the tack) is extremely nice and her work is 110%! She makes the bridles, breastcollars, etc., exactly to your measurements. Here is her website: Higher Mark ( http://www.highermark.com/ -- in case the link doesn't work). She is really, really good with questions!
I had her make me a halter/bridle combo and it fit so well and looked so good that I decided to purchase a matching breastcollar. Again, perfect fit...she made it exactly to my measurements! And my POA is really a strange "horse" to fit. =)