<s>[INST] In Copper T pack expiry dates are written. SO may i know which part of cu t device gets expired  because in some pack Mfg and exp date gap will beof just 2-3 years but the cu t is of 5-10 yrs of duration. So bit confused what is the significance of exp date and which part get expired. Dr Paras. [/INST] hi,you have to see the expiry date before insertion.it should not be beyond the expiry date at the time of insertion as the duration of efficacy is much longer.all the best. </s>