coil balancing spring

A quick learner from portland,oregon says:
May 15, 2023
my old springs are # 840 and is equivalent to 150 series but I don't know what lb it is. also need
2 ea. coil balance shoe 15-140
2 ea. coil bushing. 15-143
2 ea. coil bushing cap 15-144
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Lauren from SWISCO responded:
May 17, 2023

Hello, thank you for posting,

If the spring is stamped with #840, take a look at the S150-8 coil spring. This spring alone can support 8 pounds of wait. If one coil is used on each side, the sash weight should be 16 pounds. Please confirm and let us know if you have any additional questions! 
Coil Balance Shoe
Coil Balance Shoe
15-140
$3.07
Coil Bushing
Coil Bushing
15-143
$0.97
Coil Bushing Cap
Coil Bushing Cap
15-144
$0.70
8 lb Series 150 Coil Balance
8 lb Series 150 Coil Balance
S150-8
$6.72
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