Montana Black Empty Markers are high quality refillable empty markers. Empty markers allow artists to customize their marker collection by filling the markers with the acid-free ink or paint of their choice, even mixing colors together to create custom colors. They feature a special pump system for optimum flow control, and come in a variety of nib sizes. Designed for all surfaces and both indoor and outdoor use. The transparent marker bodies allow for easy assessment of remaining marker content. Perfect in combination with all Montana BLACK Paint and Ink Refills This set features the 15mm Standard, 10mm Chisel, 8mm Round, 18mm Crusher, and 10mm Crusher. The Montana CRUSHER is a premium squeeze marker and features a high quality mohair tip offering a broad spectrum of marking possibilities.