Is The BulletSafe Level IIIA Vest Really That Safe

How do I know what vest size is best for me? The seller is zahalorg and is located in 60850. Manufactured with 24 layers of Goldflex Protects against most handgun threats. Black police force bullet-proof / body armor vest level iiia 3a size l large 14,5 19 37 49 cm. 4-7 days(South America) 4-6(Australia).