It says something about how much the manufacturer stands behind the product. Black metal frames are made overseas. Expect to wait for a part if something breaks or if youre past that 90 day warranty, expect to pay for all replacement parts and associated costs to get your frame up and running again. Consider too that parts may also no longer be available should something break. Metal bars allow mattresses to slide into and through the gaps between each bar.
But if space is at a premium and you will only occasionally sleep on your futon best, than the tri-fold will certainly suffice. The best futon bed mattress is the one that best suits your requirements. Consider the space you have available, and what will be the main function of the futon bed mattress. If the futon is going to be used regularly for sleeping on, then most consumer reviews of futon beds tend to favour the bi-fold futon frame and mattress.
When folded, the bi-fold futon bed mattress has a wider seating area than does the tri-fold futon bed mattress. The bi-fold futon looks much more like a traditional sofa, whereas the tri-fold futon looks more like a two seat sofa. If space is very limited you may want to consider buying a tri-fold futon bed mattress, but if not, the bi-fold futon bed mattress usually looks far more pleasing to the eye.
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