Balance Spring Replacement

Hey there. Your balance looks both like our Series 351 and Series 390. The only difference between these two balances is the depth measurement of the bottom balance shoe. The depth measurement of the bottom shoe for the Series 351 is 1" and for the Series 390 is 1-1/8". You will need to measure the depth of your bottom shoe, like in the diagram below to determine which of the two balances would make the better match. As for the length of the balance, you want to measure it from metal to metal excluding the nylon fittings. Since your stamping does not correspond to any of our stampings, you will need to weigh your sash on a scale and refer to the sash weight chart listed on the product page.