This high quality cap is designed to “Slip-in’ rigid stove pipe of flexible relining systems and is made with 24 guage type 304 stainelss steel. This versatile cap can also be used on round masonry chimneys. Available in 9 stock sizes from 4″ to 12”. Also available in any custom size you need and in 100% Copper, not Copper-Plated Stainless Steel. A 5/8″ spark arrestor available on all models.