A big pile of injection molded plastic, but seems to work - Tipton Best Gun Vise

Honestly, this seem pretty cheesy. Just pieces of molded plastic, but it does actually hold a rifle pretty well for light maintenance like cleaning and adjustments. When the buttstock is clamped with the cam lock clamps the whole support piece flexes and spreads apart. But it is quite adjustable to accommodate most rifles and for the price, it seems to be OK. Adding the Wheeler AR-15 mag well vise block is a good idea if you have an AR pattern rifle. I've only used mine to clean an AR so it hasn't been really put to the test yet.