Wrangler plaid pearl snap button down shirt blue

Wrangler plaid pearl snap button down collared western shirt. White with metallic blue and silver, and black mini check plaid. Black pearl snap buttons. Long sleeves. Good preowned condition with minor general wear. Materials/size tag is not readable. Thinking it is a small but please review measurements. Pit to pit, laid flat: 20" Length, from shoulder to shortest point of rounded hem: 20"