I'm a relatively muscular guy with big arms. I was measuring my blood pressure with regular bp cuff and the readings where high. This made me wonder why since I was in good shape and ate healthy. After doing research, I found out that size of the bp cuff makes a big difference. After purchasing a sized cuff that fits my arm size, I found out my blood pressure was within normal good limits. Make sure to measure your arms circumfrance in a relaxed state in centimeters and buy the appopriate sized cuff. This product is a good one, especially for its price.