The adjustable timer automatically presets the welding time producing a consistently flat, 8” to 16” wide seal. Seals 0.025mm to 0.15mm thick polythene bags. These units come equipped with Teflon coated sealing elements that will only get hot during the sealing period. These are the perfect machines for short-run sealing of poly bags. Instruction of use: . Simply place bag between the sealing bars and press down. . Instant Sealing. . No warm-up required.