Ergo prides itself on designing accessories for superior performance by creating a better interface between the shooter and the firearm. The Never Quit Magwell Grip reconfigures the squared shape of the AR/M4 magazine well into an ergonomic and comfortable grip option. Made of Santoprene, it is oil and solvent resistant and easy to install. It fits AR-15/M-16 lower receivers with a removable trigger guard. It does not fit AR-10 large frame receivers or receivers with a permanently attached trigger guard.