PEAK JS1 Replacement Head PEAK offers replacement heads, allowing you to convert your JS2 product to a JS1 product. This gives you the ability to increase the range of hook sizes you can tie without having to purchase a whole new vise. All necessary tools to accomplish this change out are included. PEAK JS2 Replacement Head PEAK offers replacement heads, allowing you to convert your JS1 product to a JS2 product. This gives you the ability to increase the range of hook sizes you can tie without having to purchase a whole new vise. All necessary tools to accomplish this change out are included. PEAK PRVLIRS Replacement Head PEAK offers the PRVLIRS-HD replacement head, allowing you to convert your PRV product to a PRVLIRS. This allows you additional hook holding flexibility without having to buy a completely new vise. All necessary tools to accomplish this change out are included.