Window channel Balance replacement

The difference between the Series 380 and Series 385 is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. The illustration below is a good reference. Now judging from your photos, it looks close. If the depth is any at all greater than 1", then the Series 385 is a safe bet--even if it's slightly less than 1-3/32", it likely just wore down from use. That said, pictures of measuring tape aren't reliable to go by, so it's best to double and triple-check to be certain. 

If there is no stamp on the balance, you'll need to obtain the exact weight of the window sash to determine the correct stamp option. Refer to the weight ranges listed alongside each stamp option on the balance shop pages. 

Comparison of the S378, S380 and S385 balance shoes.