Mastic Silicone Caulking Gun| Faimghd Heavy-Duty Heavy gauge steel Ribbed finger grips Double spring mechanism Capacity: 425ml Faithfull Heavy-Duty Mastic Silicone Caulking Gun 425Ml | Faimghd To deliver a superior performance, heavier gauge steel is used throughout the construction, and the ribbed finger grips on the larger handle ensure extra user comfort through 360°. The ratchet has a double spring mechanism for positive and precise sealant feed when the trigger is pulled, and an instant return upon release.