This Listing is for Brand New High Quality Large Capacity (M Size) Aluminum Bobbin for Gammill Quilters. This “M style” bobbin measure 1″ in diameter and 3/8″ thick. Aluminum bobbins are considered the Top-End “Luxury Bobbins”. They offer less resistance which translates to less drag to the bobbin thread tension. These bobbins have winder slots. Also fit HQ16 by Handi Quilter, HQ18 Avante, A-1 LongArm Quilter Tin Lizzie 18 Long Arm regular and Tin Lizzie 18 LS Models Gammill: QUILTERS Nolting’s: QUILTMASTERS.