The Sig Sauer TXG Tungsten Infused Grip Module uses tungsten-infused polymer that is then molded into the part. This patent-pending process results in a grip module that has the weight of steel and the flex of polymer. Install your P320 Fire Control Unit into the TXG, and you'll have one of the flattest, softest shooting pistols on the range. Requires complete P320 Fire Control Unit Note: This grip module does not includes the extended magwell and internal weight.The X-Series Grip Modules will only fit new style magazines with the circular SIG SAUER logo and square locking tab on the bottom of the basepad. Mags marked "SIG SAUER" with circular locking tabs require modification to properly fit. Newer style basepads and locking plates are available for sale.