The key of doors and windows is the sealing,and the sealing strips play the important role in the doors and windows.The material of the sealing strip used in the market is generally modified by PVC.And the key function of the soft PVC  is the quality of the plasticizer which should be added into it.And with the price of the various petrochemical products rising,the price of the rubber products,such as the sealing strips is also rising.
In the producing process,the investment of the sealing strip accounts for a small proportion,but the function of the sealing strip cannot be negligible.Therefore,do not select those products which are faked and false in order to reduce the cost.And the identification of the sealing strip is very simple.
1.smell the sealing strip and identify if there is stinky,the normal PVC material is with a little smell of alcohol.
2.wrap the sealing strip on the profile tightly,and then place it at a  high temperature in a certain period(put it on the roof or somewhere fulled with sunshine).And then  check if theconnecting surface of the profile and the sealing strip is defaced and discolored,and check if the dust on the surface of the sealing strip is becoming yellow,being oiled or stinky. 
3.Some cheaper seals will have a lot of fillers,so the surface will not be bright,and those  that are very cheap and not suitable to use.
4.Look at the specific gravity.In order to seek the quantity,many factories will use the the talcum powder,and calcium as the filler to increase the proportion of sealing strip.When stretch the sealing strip with the calcium back and forth several times,its surface will appear a amount of white powder.
In conclusion,please check if there is oil on the surface of the sealing strip,and then check its flexibility,smell if it is stinky.
If you want the sealing strips of the door hardware accessories play the important role to make the room warm,should choose the good sealing strip.