Sealant gun, that is. It's a Tajima Convoy CNV100SP12, to be exact. Tajima do lots of different models but this is one of the ones that has what they call Auto Flow Stop, which is a posh way of saying that after every squeeze of the trigger, the piston retracts a few millimetres, enough to stop the sealant/adhesive/whatever continuing to ooze out of the nozzle. As long as it isn't too viscous, that is. Used it today on my kitchen worktop with some DC785+ and it's definitely an improvement on guns that don't have that feature. Under £23 delivered, off Amazon.