The Beiter Box Steel upgrade replaces the base and front pieces with stainless steel versions capable of holding alot more weight. As a guide. 

BEITER V-BOX STEEL: Thanks to the stainless steel shells, the Membrans can be used with different weights

• #1 : 6 oz (180g).
• #3 : 10 oz (300g).
• #5 : 16 oz (450g).
• #7 : 25 oz (710g).