Exchanges are generally carried out to improve a collection by replacing duplicate or no-longer-needed specimens with specimens that meet the current wants or needs of the institution.

The expectation is that the specimens exchanged will be of like kind or like value. In principal, almost any specimen can be traded; however, there are some specimens that probably should not be eligible for exchange: type specimens, specimens on display, one-of-a-kind specimens, or those covered by a gift restriction might not be appropriate for exchange without substantial justification. 

In an exchange, proper de-accessioning procedures should be followed.