These are 'knock' (click-type) pens.. that cap on the top is just for style and balance, click it down to propel the point. Very comfortable, fine 0.5mm gel ink. Writes smoothly, dries quickly, refillable - you'll see the refill for each color listed together with the pen. 

Overall length: 5.5"x 0.5" x 0.63" (149mm x 12.7mm x 16.0mm) with refill. Cap cover is ink color. Made in Japan; ink South Korea.