The Wilson Combat® 1911 ETM.45 ACP 8-Round Flat-Wire Spring & Follower Kit is a cost-effective magazine upgrade kit that is designed for heavy-duty, field-ready performance. It includes a maximum strength, flat wire MAX steel spring that is up to 25% stronger than stock 1911 magazine springs for superior reliability with defensive and +P loads. Corrosion, heat, and stress resistance are all long-lasting thanks to the sturdy, heat-treated polymer follower. Compatible with magazines of the 500, 500B, 500C, and 500BC series. Additionally, this ETM Spring/Follower Kit will retrofit into all ETM 8-round.45 ACP magazines as well as change all full-size magazines from the 47 Series into 7-round magazines and compact magazines from the 47 Series into 6-round magazines.