Only makings on the spring is a. D. And the plastic part has a f on it

A home owner from 26041 says:
May 15, 2020
Need 2 of these.
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Bob from SWISCO responded:
May 18, 2020

This looks like a 15-177. This pivot shoe uses our Series 152 Coil Springs. A stamp of 'D' suggests this might be a 4 lb coil spring, in which case you'd need the S152-4. Let me know if you have any other questions. 
Coil Balance Shoe, Slate Blue
Coil Balance Shoe, Slate Blue
15-177
$3.47
4 lb Series 152 Coil Balance
4 lb Series 152 Coil Balance
S152-4
$4.70
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