TWSBI fountain pens are loved for their high quality and affordability, offering advanced filling mechanisms normally reserved for much more expensive fountain pens. The TWSBI ECO (short for "economical") provides the same high-quality, high-capacity piston filler as the TWSBI Diamond 580 at an even lower price. It features a sleek, transparent barrel and a hexagonal screw-on cap that can be posted securely on the back of the pen. The piston filling mechanism is easily operated by twisting the knob at the end of the barrel counter-clockwise to extend the piston, submerging the nib in ink, then screwing the knob tight to retract the piston, drawing ink into the pen straight from the bottle. There's no need for cartridges or a converter! Be careful—operating the piston while ink is in the pen will cause ink to leak out of the pen.
This limited-edition pen features a light brown cap and piston knob, accented with a bronze-colored nib and trim.
In keeping with their philosophy of promoting the traditional experience of using a fountain pen, TWSBI has designed this pen to be completely self-serviceable. It comes with a wrench and a vial of silicone grease you can use for at-home maintenance.
Notes:
- TWSBI pens with rose gold or bronze nibs may write broader than their silver nibs.
- Some TWSBI ECO Fountain Pens have nibs and feeds that are very difficult to remove. Attempting to remove the nib and feed forcefully may damage the feed.
- This pen only uses bottled ink, which is not included with this pen. Check out our collection of bottled fountain pen inks here!
- This pen may come with ink residue in the nib from being dip tested by TWSBI at the factory. As with all new fountain pens, JetPens recommends giving your TWSBI a good cleaning before you use it.
| Model Number | TWSBI M7441010 |
| Manufacturer | TWSBI |
| Accent Color | Light Brown |
| Body Color | Clear |
| Body Material | Plastic |
| Capped or Retractable | Capped - Screw On |
| Clip Material | Metal |
| Clippable | Yes |
| Converter Included | No |
| Diameter - Grip | 10.0 mm |
| Diameter - Max | 15.2 mm |
| Eyedropper Convertible | No |
| Filling Mechanism | Piston |
| Fountain Pen Capacity | 1.5 ml |
| Gift Set | No |
| Grip Color | Clear |
| Grip Material | Plastic |
| Ink Refillable | Yes |
| Length - Capped | 13.9 cm / 5.5 inches |
| Length - Posted | 16.8 cm / 6.6 inches |
| Length - Uncapped | 13.1 cm / 5.2 inches |
| Nib Color | Copper |
| Nib Material | Steel |
| Nib Size | Medium |
| Tip Replaceable | No |
| Tip Type | Nib |
| Weight - Barrel (Empty) | 0.31 oz / 9 grams |
| Weight - Cap | 0.43 oz / 12 grams |
| Weight - Whole Pen (Empty) | 0.75 oz / 21 grams |
Q: Can this pen be used with ink cartridges?
No, it can only be filled with bottled fountain pen ink.
Q: Is this pen's grip section round or contoured for guided finger placement?
The grip section of the TWSBI ECO is round except for the flared section near the tip, which is triangular and can be used to guide finger placement if you hold the pen near the front end of the grip section.
Q: Does this pen use Japanese or Western nib sizing?
All TWSBI fountain pen nibs are made in Germany and use Western nib sizing standards.
Q: How do I clean out the ink that is stuck between the inner and outer caps of this pen?
The TWSBI pen's cap can be taken apart for cleaning. To clean your pen's cap, follow these steps:
1. Wrap a wide rubber band around the eraser end of a wooden pencil. It is best to try to cover the metal band around the pencil with the wrapped rubber band to prevent accidental scratching of your TWSBI cap.
2. Gently but firmly stick the eraser end of the pencil into the cap of your TWSBI pen, as far as the pencil will go.
3. Slowly pull the pencil away from the cap, with the goal of taking the inner cap with the pencil. You may need to repeat steps 2-3 a few times before the cap will pop out.
4. Rinse, soak, and dry the caps.
5. Remove the rubber band from the wooden pencil.
6. Gently but firmly push the inner cap back into the outer cap, using the eraser end of the wooden pencil. Be careful not to scratch the inner cap with any part of the wooden pencil.
1. Wrap a wide rubber band around the eraser end of a wooden pencil. It is best to try to cover the metal band around the pencil with the wrapped rubber band to prevent accidental scratching of your TWSBI cap.
2. Gently but firmly stick the eraser end of the pencil into the cap of your TWSBI pen, as far as the pencil will go.
3. Slowly pull the pencil away from the cap, with the goal of taking the inner cap with the pencil. You may need to repeat steps 2-3 a few times before the cap will pop out.
4. Rinse, soak, and dry the caps.
5. Remove the rubber band from the wooden pencil.
6. Gently but firmly push the inner cap back into the outer cap, using the eraser end of the wooden pencil. Be careful not to scratch the inner cap with any part of the wooden pencil.
Q: How much ink can this pen hold?
The TWSBI ECO can hold up to about 1.7 ml of ink. For the largest possible filling, follow these steps:
- Cycle the piston down and up several times with the nib submerged in ink.
- Take the pen out of the ink and hold it nib-up. Wait several seconds for the air bubbles inside the barrel to travel up to the nib.
- Twist the piston knob slowy to force the remaining air out of the pen. Stop when ink begins to well up where the nib and feed meet the grip section.
- Submerge the nib in ink again and twist the piston knob back to fill the pen to maximum capacity.
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Product Specifications
| Model Number TWSBI M7441010 |
TWSBI M7441010 |
| Manufacturer TWSBI |
TWSBI |
| Accent Color Light Brown |
Light Brown |
| Body Color Clear |
Clear |
| Body Material Plastic |
Plastic |
| Capped or Retractable Capped - Screw On |
Capped - Screw On |
| Clip Material Metal |
Metal |
| Clippable Yes |
Yes |
| Converter Included No |
No |
| Diameter - Grip 10.0 mm |
10.0 mm |
| Diameter - Max 15.2 mm |
15.2 mm |
| Eyedropper Convertible No |
No |
| Filling Mechanism Piston |
Piston |
| Fountain Pen Capacity 1.5 ml |
1.5 ml |
| Gift Set No |
No |
| Grip Color Clear |
Clear |
| Grip Material Plastic |
Plastic |
| Ink Refillable Yes |
Yes |
| Length - Capped 13.9 cm / 5.5 inches |
13.9 cm / 5.5 inches |
| Length - Posted 16.8 cm / 6.6 inches |
16.8 cm / 6.6 inches |
| Length - Uncapped 13.1 cm / 5.2 inches |
13.1 cm / 5.2 inches |
| Nib Color Copper |
Copper |
| Nib Material Steel |
Steel |
| Nib Size Medium |
Medium |
| Tip Replaceable No |
No |
| Tip Type Nib |
Nib |
| Weight - Barrel (Empty) 0.31 oz / 9 grams |
0.31 oz / 9 grams |
| Weight - Cap 0.43 oz / 12 grams |
0.43 oz / 12 grams |
| Weight - Whole Pen (Empty) 0.75 oz / 21 grams |
0.75 oz / 21 grams |
Customer Reviews
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TWSBI lovely colors....March 7, 2025Verified PurchaseTWSBI lovely colors. TWSBI is a great pen company for those on a budget. I'd love to seer more color options for the 580 Diamond, but the ECO performs well and can hold up.1 person found this helpfuldmac2d2c1ch
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This is a great fountain...July 30, 2025Verified PurchaseThis is a great fountain pen for the price. Performs better than my more expensive ones. The writing with these nibs definitely leans thicker than with other M nib pens, but I like the result and shading. The caffe color looks particularly good with blue ink!fotih
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Super easy to use, lovely...June 26, 2025Verified PurchaseSuper easy to use, lovely color, all around perfectcryptcke
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Beautiful smooth writing...May 19, 2025Verified PurchaseBeautiful smooth writing pen. I have enjoyed writing with it- my son has also!srdirck
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I always wanted a TWSBI,...April 8, 2025Verified PurchaseI always wanted a TWSBI, so getting this caffè bronze limited edition felt great finally adding one to my collection. Writes incredibly well and smooth with no issues out of the box. Definitely keeping this one inked for a long time.GarudaPanzer