Bro. David is close.
When the Double Barrel Trap gun was introduced in 1920, the 'Trap Package' included a flat BTFE, then optional Schnabel in 1922, with the reinforced barrel lug, AE, HOT, and in 1925 a ventilated rib (designed by Stephen J. Gilles the General Manager), with two ivory beads, and recoil pad. Parker offered a VR on their doubles starting in 1923. I believe on introduction in 1925 the Ithaca NID could be ordered with a VR.

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