KelTec introduced the SUB-SDP Nub Sub, a folding 9mm pistol-caliber carbine compatible with extended Glock magazines. The model may count among the smallest production 9mm pistol-caliber carbines and uses a compact layout similar to the SUB2000 series that supports suppressors. Testers who put 600 rounds through it reported quiet reliable function without over-gassing when a suppressor was attached plus tight groups at 25 yards.