Rare-earth magnets securely holds the bottom in place. Special design push through block quickly and easily ejects the 1/2 oz puck. Works well with 3x5 plates, or use 2 bagged pucks for 5x7 or larger plates. Inner tray (puck) dimensions are: 1-3/4" x 3-1.2" x 1 deep, suitable for 10-14 gram (max 1/2 oz) loads. To be used with an arbor press for best results, will also with with a using a c-clamp.Hand made 95u filter bags. Food grade high temperature nylon. 95u micron filtration, perfect for dry flower. Middle folding design means both long sides are folded. Tested and proven efficiency, no heavy thick seams to soak up valuable rosin means higher yields. Comes in 30, or 100 pack with pre-press mold, which is matching sized to produced the perfect pucks for these bags. This item is made of aluminium and nylon.