The Stanley HT350 FatMax Pro Hammer Tacker has a retractable integral knife blade which allows for easy cutting prior to fixing or tacking in place. Designed specifically for roofing, insulations, underlay and felting applications etc. with bottom staple loading for quick and easy loading and a captive staple pusher. Specification: Fires: Heavy-Duty Type G Staples: 8-12mm. Blade Types: 11-921, 11-937, 11-987