The Kel-Tec Sub-SDP is a folding, pistol-caliber semi-automatic pistol chambered in 9mm, built on the operating concept of Kel-Tec's SUB2000 folding carbine but scaled down into a pistol-length package. It runs a 6-inch threaded barrel, holds 17+1 in a Glock-style magazine, and includes a factory-installed adjustable pistol brace. An integrated M-LOK accessory rail on the forend gives mounting points for a light or laser without adding much bulk to the folded profile.