The reason we offer so many types of tie cords is due to customer preference. Your preferences can be affected by your yard type (grass, bare ground, and soil type) or size, or housing type (teepee, barrels, etc.), and also your own personal preferences, like how easy you want the hitch to be able to be removed or attached to the bird. We can answer questions about each individual type if you want to try a type you have never tried before, but we can not and will not guarantee that you will like what you buy. Each of our types of cords and hitches work in the situations they were designed for (most situations) but some are better at this and some are better at that. If you desire to change types or try tie cords for the first time, we suggest ordering a sample(s) of the cords you would like to try, before ordering a large quantity. We do not refund or exchange tie cords that have been used, just because you donít like them. We will refund or exchange cords or hitches that have not been used, if the cords are not custom length. Or, we can replace the unused hitches on cords (for a fee, and you will have to pay shipping both ways) if you decide you do not like them. We may be able to exchange the actual cord in the same way (you will pay all costs) , on unused tie cords, if you decide you donít like the type cord or length of cord you purchased. Sometimes it would be cheaper, for you to just buy the replacement parts and install them yourself, so think about that. We do offer a 6 month warranty on cords and hitches and will replace any defective parts or fix defective workmanship. Shipping must be paid by you to return the cords to us for warranty work, unless the cords are unused and it has been 30 days or less since you received them, then we will pay the return shipping to us. We pay the shipping to get the repaired cords back to you, on any warranty work. It is possible in certain instances (with adequate proof of the problem), that we can send you the parts for the warranty so you can fix the problem yourself, if you desire. This may speed up the warranty service. Please check your tie cords before putting your birds on them for any wear or defects, by giving them a good hard pull (the average person should not be able to break a new cord by pulling on it with one hand and arm (without putting all your body weight into it)). Also check and make sure the hitch fits your birdís leg (not too loose or too tight) and that it can not get out of the hitch after the hitch is properly closed. We will not be responsible for anything except the tie cord parts which fail, if your bird(s) should get off the cord, so do your part and check all tie cords before using them, whether they are new or old cords. Cords that are custom length (standard length for nylon cords is 8í and for rubber cords is 7í), can not be returned for a refund even if unused, although we may be able to help you out as mentioned earlier in this paragraph, if you want an exchange. Used cords can not ever be returned for a refund only for warranty work.