Elastic straps are used to wrap the heart rate transmitter around the chest. 

Available in 3 sizes: 
Small:
12" shortest, 20" middle, 
30" extended 
Medium: 16", 28", 48" 
Large: 22", 43", 66" 

To measure, determine your chest size, for women, directly below the bust.  Then subtract 11" for the transmitter length. 

(Ex: 44" chest - 11"= 33" medium) 

$ 6.00 each