Please simply request your size within the eCrater purchase form
(during check-out, there will be a "Note For Seller" field available where you can write it).
Shortly after your purchase, you will receive our order eMail confirmation where we will confirm
your order, estimated shipping and delivery date, and your size choice as well.
You can choose your desired size out from this list, that includes the aproximate armpit-to-armpit width measurements:
XS = 18 inches
S = 19 inches
M = 20 inches
L = 21 inches
XL = 22 inches
XXL = 23 inches