Certain teed Coil Spring

A quick learner from Downingtown Pa says:
September 29, 2016
I have certain teed single hung Windows. Each side take two coil springs 405J. What is the difference between the 171-405 and 170-405?
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Paul from SWISCO responded:
September 30, 2016
Hello! The Series 171 is specifically meant to be used in coil balance systems that use more than one spring. the Series 170 spring, which has a short tongue, would sit on the bottom, while the Series 171 would sit on top and use its longer tongue to reach all the way down to install.
405 Series 170 Coiled Balance Spring
405 Series 170 Coiled Balance Spring
S170-405
$6.52
405 Series 171 Coiled Balance Spring, Long
405 Series 171 Coiled Balance Spring, Long
S171-405
$6.55
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