High density foam has a compression rate of 44 lbs. It features the perfect amount of cushioning and stiffness. Its soft but still holds its firmness and support for an individual to sit on it without compressing the foam too much. Compression = firmness compression (not density) is what determines firmness. If you don't want a cushion that's hard as a rock or a mattress that sinks when you sit on it, you have to check the compression or ILD number.
24 X 120 High Density Upholstery Foam Cushion seat Replacement, Upholstery Sheet, Foam Paddingmade in USA Fast Shipping
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GoTo Foam 2 Height x 24 Width x 96 Length 43ILD (Firm) Upholstery Cushion Made in USA : Arts, Crafts & Sewing
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FoamTouch Upholstery Cushion High Density Standard, Seat Replacement, Sheet, Padding, 3 L x 24 W x 72 H : : Home & Kitchen
FoamRush 3 H x 15 W x 75 L High Density Upholstery Foam Cushion (Chair Cushion Bench Foam for Dinning Chairs, Bench Seat Cushion Replacement, Foam Rubber Padding) : Arts, Crafts
FoamTouch 4x24x72MDF Medium Density (semi Firm) Upholstery Foam, 1 Count (Pack of 1), White : Everything Else
Foamtouch Upholstery Foam Cushions
SUBRTEX Cushion Insert Upholstery Pad High Density Seat Square Replacement for Loveseat Sofa Firm Quality Foam Sheet, for DIY, 5''Height x 24''Width x 72''Length, 5H x 24W x 72L, White