How to measure your model
1) Head size - measure from corner of the
mouth over the poll to the other corner of
mouth
2) Brow band - since this part of the bridle is
not adjustable, make sure to measure
exactly the length from end of one brow
band loop to end of the other one.
3) Troathlatch - measure from the end of brow
band loop under the throat to the other end of
the brow band loop
4) Noseband - measure all around the nose in mid way
between the cheekbone and corner of the mouth
5) Rein length - measure from corner of the mouth to the spot
where rider`s hands would be
6) Barrel - A/ measure all around model`s belly in the widest part (start
at the top of withers, under the belly and back to the starting point)  
        B/ measure all around belly at the lowest part of back
7) Midback - measure from the withers to the croup
I need to know the following 8 sizes to make sure the finished tack will fit your model well.
Please do not add anything to the measurements, I will adjust them accordingly to give some extra wiggle room. ;)
In case you`d prefer to send your model in for fitting, just let me know!